IndiMail

Some mail providers like hotmail, yahoo restrict the number of connections from a single IP and the number of mails that can be delivered in an hour from a single IP. To increase your ability to deliver large number of genuine emails from your users ... [More] to such sites, you may want to send out mails from multiple IP addresses.IndiMail has the ability to call a custom program instead of qmail-local(8) or qmail-remote(8). This is done by defining the environment variable QMAILLOCAL or QMAILREMOTE. qmail-remote(8) can use the environment variable OUTGOINGIP to set the IP address of the local interface when making outgoing connections. By writing a simple script and setting QMAILREMOTE environment variable pointing to this script, one can randomly chose an IP address from the control file/var/indimail/control/outgoingipThe script below also allows you to define multiple outgoing IP addresses for a single host. e.g. you can create the control file to send out mails from multiple IPs only for the domain hotmail.com/var/indimail/control/outgoingip.hotmail.comLet us name the below script balance_outgoing% su# echo "/var/indimail/bin/balance_outgoing" > /service/qmail-send.25/variables/QMAILREMOTE# svc -d /service/qmail-send.25# svc -u /service/qmail-send.25# exit%Finally the balance_outgoing script can be placed with execute bit in /var/indimail/bin#!/bin/sh# This scripts expects qmail-remote arguments on command line# argv0          - qmail-remote# argv1          - host   (host)# argv2          - sender (sender)# argv3          - qqeh   (qmail queue extra header)# argv4          - size# argv5 .. argvn - recipients# #host=$1sender=$2qqeh=$3size=$4shift 4cd /var/indimailif [ " $CONTROLDIR" = " " ] ; then    FN=/var/indimail/control/filterargselse    FN=$CONTROLDIR/filterargsfiif [ -n "$SPAMFILTER" -o -n "$FILTERARGS" -o -f $FN ] ; then    # execute spawn-filter if you have filters defined for remote/local deliveries    PROG="bin/spawn-filter"else    PROG="bin/qmail-remote"fiif [ " $CONTROLDIR" = " " ] ; then    if [ -f /var/indimail/control/outgoingip.$host ] ; then        IP=(`cat /var/indimail/control/outgoingip.$host`)    elif [ -f /var/indimail/control/outgoingip ] ; then        IP=(`cat /var/indimail/control/outgoingip`)    else        exec -a qmail-remote $PROG "$host" "$sender" "$qqeh" $size $*    fielse    if [ -f $CONTROLDIR/outgoingip.$host ] ; then        IP=(`cat $CONTROLDIR/outgoingip.$host`)    elif [ -f $CONTROLDIR/outgoingip ] ; then        IP=(`cat $CONTROLDIR/outgoingip`)    else        exec -a qmail-remote $PROG "$host" "$sender" "$qqeh" $size $*    fifiIP_COUNT=${#IP[*]}if [ $IP_COUNT -gt 1 ] ; then    i=`expr $RANDOM % $IP_COUNT`    export OUTGOINGIP=${IP[$i]}fiexec -a qmail-remote $PROG "$host" "$sender" "$qqeh" $size $* [Less]

Some mail providers like hotmail, yahoo restrict the number of connections from a single IP and the number of mails that can be delivered in an hour from a single IP. To increase your ability to deliver large number of genuine emails from your users ... [More] to such sites, you may want to send out mails from multiple IP addresses.IndiMail has the ability to call a custom program instead of qmail-local(8) or qmail-remote(8). This is done by defining the environment variable QMAILLOCAL or QMAILREMOTE. qmail-remote(8) can use the environment variable OUTGOINGIP to set the IP address of the local interface when making outgoing connections. By writing a simple script and setting QMAILREMOTE environment variable pointing to this script, one can randomly chose an IP address from the control file/var/indimail/control/outgoingipThe script below also allows you to define multiple outgoing IP addresses for a single host. e.g. you can create the control file to send out mails from multiple IPs only for the domain hotmail.com/var/indimail/control/outgoingip.hotmail.comLet us name the below script balance_outgoing% su# echo "/var/indimail/bin/balance_outgoing" > /service/qmail-send.25/variables/QMAILREMOTE# svc -d /service/qmail-send.25# svc -u /service/qmail-send.25# exit%Finally the balance_outgoing script can be placed with execute bit in /var/indimail/bin#!/bin/sh# This scripts expects qmail-remote arguments on command line# argv0          - qmail-remote# argv1          - host   (host)# argv2          - sender (sender)# argv3          - qqeh   (qmail queue extra header)# argv4          - size# argv5 .. argvn - recipients# #host=$1sender=$2 qqeh=$3 size=$4 shift 4cd /var/indimail if [ " $CONTROLDIR" = " " ] ; then     FN=/var/indimail/control/filterargs else     FN=$CONTROLDIR/filterargs fi if [ -n "$SPAMFILTER" -o -n "$FILTERARGS" -o -f $FN ] ; then     # execute spawn-filter if you have filters defined for remote/local deliveries     PROG="bin/spawn-filter" else     PROG="bin/qmail-remote" fi if [ " $CONTROLDIR" = " " ] ; then     if [ -f /var/indimail/control/outgoingip.$host ] ; then         IP=(`cat /var/indimail/control/outgoingip.$host`)     elif [ -f /var/indimail/control/outgoingip ] ; then         IP=(`cat /var/indimail/control/outgoingip`)     else         exec -a qmail-remote $PROG "$host" "$sender" "$qqeh" $size $*     fi else     if [ -f $CONTROLDIR/outgoingip.$host ] ; then         IP=(`cat $CONTROLDIR/outgoingip.$host`)     elif [ -f $CONTROLDIR/outgoingip ] ; then         IP=(`cat $CONTROLDIR/outgoingip`)     else         exec -a qmail-remote $PROG "$host" "$sender" "$qqeh" $size $*     fi fi IP_COUNT=${#IP[*]} if [ $IP_COUNT -gt 1 ] ; then     i=`expr $RANDOM % $IP_COUNT`     export OUTGOINGIP=${IP[$i]} fi exec -a qmail-remote $PROG "$host" "$sender" "$qqeh" $size $* [Less]

IndiMail allows a mechanism by which you can use your own script/program to handle bounces. All bounces in IndiMail is generated by qmail-send. qmail-send generates a bounce when qmail-lspawn or qmail-rspawn reports a permanent failed delivery. A ... [More] bounce is generated by qmail-send by injecting a new mail in the queue using qmail-queue. This bounce generation by qmail-send can be modified in three ways1. Using environment variable BOUNCEPROCESSORWhen you define the environment variable BOUNCEPROCESSOR as a valid path to a program or script, the program gets called whenever a delivery fails permanently. The program runs with the uid qmails and is passed the following five argumentsbounce_file bounce_report bounce_sender original_recipient bounce_recipientTo set BOUNCEPROCESSOR, you would do the following# echo "path_of_your_bounce_processor" > /service/qmail-send.25/variables/BOUNCEPROCESSORThere are few email marketing companies who are using BOUNCEPROCESSOR to insert the status of all bounces in MySQL table for their email marketing campaigns.2 Using environment variable BOUNCERULES or control files bounce.envrules.Using envrules, you can set specific environment variables only for bounced recipients. The format of  this  file  is  of  the  formpat:envar1=val,envar2=val,...]where pat is a regular expression which matches a bounce recipient.  envar1, envar2 are list of environment variables to be set. If var is omitted, the environment variable is [email protected]:CONTROLDIR=control2,QMAILQUEUE=/var/indimail/bin/qmail-nullqueuecauses all bounces generated for the sender [email protected] to be discarded.3. Using BOUNCEQUEUE environment variable to queue bouncesqmail-send  uses  qmail-queue to queue bounces and aliases/forwards. This can be changed by using QMAILQUEUE environment variable. If a different queue program is desired for bounces, it can be set by using BOUNCEQUEUE environment variable.e.g# echo /var/indimail/bin/qmail-nullqueue > /service/qmail-send.25/variables/BOUNCEQUEUEdisables bounces system-wide. Though disabling bounces may not be the right thing to do but in some situations where bounces are not at all needed, disabling bounces will surely result in performance improvements of your system, especially so if your system does mass-mailing. [Less]

IndiMail allows a mechanism by which you can use your own script/program to handle bounces. All bounces in IndiMail is generated by qmail-send. qmail-send generates a bounce when qmail-lspawn or qmail-rspawn reports a permanent failed delivery. A ... [More] bounce is generated by qmail-send by injecting a new mail in the queue using qmail-queue. This bounce generation by qmail-send can be modified in three ways 1. Using environment variable BOUNCEPROCESSOR When you define the environment variable BOUNCEPROCESSOR as a valid path to a program or script, the program gets called whenever a delivery fails permanently. The program runs with the uid qmails and is passed the following five arguments bounce_file bounce_report bounce_sender original_recipient bounce_recipient To set BOUNCEPROCESSOR, you would do the following # echo "path_of_your_bounce_processor" > /service/qmail-send.25/variables/BOUNCEPROCESSOR There are few email marketing companies who are using BOUNCEPROCESSOR to insert the status of all bounces in MySQL table for their email marketing campaigns. 2 Using environment variable BOUNCERULES or control files bounce.envrules. Using envrules, you can set specific environment variables only for bounced recipients. The format of  this  file  is  of  the  form pat:envar1=val,envar2=val,...] where pat is a regular expression which matches a bounce recipient.  envar1, envar2 are list of environment variables to be set. If var is omitted, the environment variable is unset. e.g. [email protected]:CONTROLDIR=control2,QMAILQUEUE=/var/indimail/bin/qmail-nullqueue causes all bounces generated for the sender [email protected] to be discarded. 3. Using BOUNCEQUEUE environment variable to queue bounces qmail-send  uses  qmail-queue to queue bounces and aliases/forwards. This can be changed by using QMAILQUEUE environment variable. If a different queue program is desired for bounces, it can be set by using BOUNCEQUEUE environment variable. e.g # echo /var/indimail/bin/qmail-nullqueue > /service/qmail-send.25/variables/BOUNCEQUEUE disables bounces system-wide. Though disabling bounces may not be the right thing to do but in some situations where bounces are not at all needed, disabling bounces will surely result in performance improvements of your system, especially so if your system does mass-mailing. [Less]

IndiMail allows a mechanism by which you can use your own script/program to handle bounces. All bounces in IndiMail is generated by qmail-send. qmail-send generates a bounce when qmail-lspawn or qmail-rspawn reports a permanent failed delivery. A ... [More] bounce is generated by qmail-send by injecting a new mail in the queue using qmail-queue. This bounce generation by qmail-send can be modified in three ways1. Using environment variable BOUNCEPROCESSORWhen you define the environment variable BOUNCEPROCESSOR as a valid path to a program or script, the program gets called whenever a delivery fails permanently. The program runs with the uid qmails and is passed the following five argumentsbounce_file bounce_report bounce_sender original_recipient bounce_recipientTo set BOUNCEPROCESSOR, you would do the following# echo "path_of_your_bounce_processor" > /service/qmail-send.25/variables/BOUNCEPROCESSORThere are few email marketing companies who are using BOUNCEPROCESSOR to insert the status of all bounces in MySQL table for their email marketing campaigns.2 Using environment variable BOUNCERULES or control files bounce.envrules.Using envrules, you can set specific environment variables only for bounced recipients. The format of  this  file  is  of  the  formpat:envar1=val,envar2=val,...]where pat is a regular expression which matches a bounce recipient.  envar1, envar2 are list of environment variables to be set. If var is omitted, the environment variable is [email protected]:CONTROLDIR=control2,QMAILQUEUE=/var/indimail/bin/qmail-nullqueuecauses all bounces generated for the sender [email protected] to be discarded.3. Using BOUNCEQUEUE environment variable to queue bouncesqmail-send  uses  qmail-queue to queue bounces and aliases/forwards. This can be changed by using QMAILQUEUE environment variable. If a different queue program is desired for bounces, it can be set by using BOUNCEQUEUE environment variable.e.g# echo /var/indimail/bin/qmail-nullqueue > /service/qmail-send.25/variables/BOUNCEQUEUEdisables bounces system-wide. Though disabling bounces may not be the right thing to do but in some situations where bounces are not at all needed, disabling bounces will surely result in performance improvements of your system, especially so if your system does mass-mailing. [Less]

IndiMail uses a modified version of qmail as the MTA. For local deliveries, qmail-lspawn reads a series of local delivery commands from descriptor 0, invokes qmail-local to perform the deliveries. qmail-local reads a mail message and delivers to to a ... [More] user by the procedure described in dot-qmail(5). IndiMail uses vdelivermail as the local delivery agent.A virtual domain is created by the command vadddomain(1).% vadddomain example.com some_passwordThe above command creates a virtual domain with delivery instructions in /var/indimail/domains/example.com/.qmail-default file. A line in this file is of the form/var/indimail/sbin/vdelivermail '' delivery_instruction_for_non_existing_userThe delivery_instruction_for_non_existing_user can have one of the following 5 formsdeletebounce-no-mailboxMaildiremailAddressIPaddressUsing delete as the delivery instruction causes IndiMail to discard all mails addressed to non-existing users. The original sender does not get notified of the delivery. On a real messaging system serving real users, you will not want to do this.The instruction bounce-no-mailbox causes a bounce to be generated to the sender in case an email is addressed to a non-existing user. This is the most common usage in .qmail-default which most IndiMail installations will haveThe instruction Maildir causes emails to be addressed to non-existing users to be saved in a Maildir. Here Maildir should refer to a full path of an existing Maildir.The instruction emailAddress causes emails to be addressed to non-existing users to be forwarded to an email address emailAddress.The instruction IPaddress causes emails to be addressed to non-existing users to be redirected to a remote SMTP server at IP IPaddress. The format of IPaddress is domain:ip:port where domain is the domain name, ip is the IP address of the remote SMTP server and port is the SMTP port on the remote SMTP server. It is expected that the non-existing user is present on the remote system. This type of delivery is used by IndiMail on a clustered setup. In a clustered setup, users are distributed across multiple server. A particular user will be located only on one particular server. However, the same domain will be present on multiple servers.In the delivery instruction in .qmail-default, you can replace vdelivermail with vfilter to perform in-line filtering use IndiMail's poweful vfilter. You can create filters using the program vcfilter. [Less]

IndiMail uses a modified version of qmail as the MTA. For local deliveries, qmail-lspawn reads a series of local delivery commands from descriptor 0, invokes qmail-local to perform the deliveries. qmail-local reads a mail message and delivers to to a ... [More] user by the procedure described in dot-qmail(5). IndiMail uses vdelivermail as the local delivery agent. A virtual domain is created by the command vadddomain(1). % vadddomain example.com some_password The above command creates a virtual domain with delivery instructions in /var/indimail/domains/example.com/.qmail-default file. A line in this file is of the form /var/indimail/sbin/vdelivermail '' delivery_instruction_for_non_existing_user The delivery_instruction_for_non_existing_user can have one of the following 5 forms delete bounce-no-mailbox Maildir emailAddress IPaddress Using delete as the delivery instruction causes IndiMail to discard all mails addressed to non-existing users. The original sender does not get notified of the delivery. On a real messaging system serving real users, you will not want to do this. The instruction bounce-no-mailbox causes a bounce to be generated to the sender in case an email is addressed to a non-existing user. This is the most common usage in .qmail-default which most IndiMail installations will have The instruction Maildir causes emails to be addressed to non-existing users to be saved in a Maildir. Here Maildir should refer to a full path of an existing Maildir. The instruction emailAddress causes emails to be addressed to non-existing users to be forwarded to an email address emailAddress. The instruction IPaddress causes emails to be addressed to non-existing users to be redirected to a remote SMTP server at IP IPaddress. The format of IPaddress is domain:ip:port where domain is the domain name, ip is the IP address of the remote SMTP server and port is the SMTP port on the remote SMTP server. It is expected that the non-existing user is present on the remote system. This type of delivery is used by IndiMail on a clustered setup. In a clustered setup, users are distributed across multiple server. A particular user will be located only on one particular server. However, the same domain will be present on multiple servers. In the delivery instruction in .qmail-default, you can replace vdelivermail with vfilter to perform in-line filtering use IndiMail's poweful vfilter. You can create filters using the program vcfilter. [Less]

IndiMail uses a modified version of qmail as the MTA. For local deliveries, qmail-lspawn reads a series of local delivery commands from descriptor 0, invokes qmail-local to perform the deliveries. qmail-local reads a mail message and delivers to to a ... [More] user by the procedure described in dot-qmail(5). IndiMail uses vdelivermail as the local delivery agent.A virtual domain is created by the command vadddomain(1).% vadddomain example.com some_passwordThe above command creates a virtual domain with delivery instructions in /var/indimail/domains/example.com/.qmail-default file. A line in this file is of the form/var/indimail/sbin/vdelivermail '' delivery_instruction_for_non_existing_userThe delivery_instruction_for_non_existing_user can have one of the following 5 forms delete bounce-no-mailbox Maildir emailAddress IPaddress Using delete as the delivery instruction causes IndiMail to discard all mails addressed to non-existing users. The original sender does not get notified of the delivery. On a real messaging system serving real users, you will not want to do this.The instruction bounce-no-mailbox causes a bounce to be generated to the sender in case an email is addressed to a non-existing user. This is the most common usage in .qmail-default which most IndiMail installations will haveThe instruction Maildir causes emails to be addressed to non-existing users to be saved in a Maildir. Here Maildir should refer to a full path of an existing Maildir.The instruction emailAddress causes emails to be addressed to non-existing users to be forwarded to an email address emailAddress.The instruction IPaddress causes emails to be addressed to non-existing users to be redirected to a remote SMTP server at IP IPaddress. The format of IPaddress is domain:ip:port where domain is the domain name, ip is the IP address of the remote SMTP server and port is the SMTP port on the remote SMTP server. It is expected that the non-existing user is present on the remote system. This type of delivery is used by IndiMail on a clustered setup. In a clustered setup, users are distributed across multiple server. A particular user will be located only on one particular server. However, the same domain will be present on multiple servers.In the delivery instruction in .qmail-default, you can replace vdelivermail with vfilter to perform in-line filtering use IndiMail's poweful vfilter. You can create filters using the program vcfilter. [Less]

A SMTP server is responsible for accepting mails from a sender and processing it for delivery to one or more recipients. In most situations, for domains which are under your administrative control (native addresses), the SMTP server should accept ... [More] mails without authentication. However, when a mail is submitted for delivery to domains which are not under your administrative control, you should accept mails only after it satisfies security considerations like having the sender authenticate itself. This is to prevent abuse of external domains using your SMTP server. A SMTP server which accepts mails for external domains without any authentication is called an open relay. The act of accepting mails for external domains for delivery is called relaying. The default configuration of IndiMail configures the SMTP as a closed system. Hence to be able to send mails to external domains, you need to setup mechanisms for relaying. There are many methods. Choose any of the below after studying them. I prefer 3 or 4 for security reasons. Have Sender's IP addresses in tcp.smtp file Use control file relayclients for IP addresses of clients allowed to relay mail through this host. Configure IndiMail to use MySQL relay table (good security) Use authenticated SMTP (good security) For allowing relay to specific domains use control file relaydomains For allowing specific users (native addresses) use control file relaymailfrom NOTE: you should use 1 & 2 only if if the host having the sender's IP is under your control and you have good security policies for the host (however what is a good security can be very subjective) Using tcp.smtp Your startup script for the qmail smtp server must use the tcpserver -x file option similar to this startup line. env - PATH="/var/indimail/bin" tcpserver -H -R -x /var/indimail/etc/tcp.smtp.cdb \ -c 20 -u 555 -g 555 0 smtp /var/indimail/bin/qmail-smtpd 2>&1 IndiMail uses -x option to tcpserver and hence you need not bother about the above line. You however need to edit /var/indimail/etc/tcp.smtp and put in lines for all static IP's that you will always want to relay access to. 127.0.0.:allow,RELAYCLIENT=”” 10.1.1.:allow,RELAYCLIENT=”” The above lines will cause RELAYCLIENT environment variable to be set for localhost and all machines on the 10.1.1 class and hence allow to relay through. Remember that any user on hosts on 10.1.1 class will be able to relay mails. You many not want this. The line having 127.0.0. will allow any client on the IndiMail host to use SMTP and relay mails. If you add any IP to tcp.smtp, you have to rebuild a cdb database tcp.smtp.cdb. You can run the following command % sudo /var/indimail/bin/qmailctl cdb NOTE: Remember that you are exposed to unrestricted relaying from any of the IP addresses listed in tcp.smtp Using control file relayclients IP addresses of clients allowed to relay mail  through  this  host.   Each address should be followed by a colon and an (optional) string that should be appended to each incoming recipient address, just as  with  the  RELAYCLIENT environment variable.  Nearly always, the optional string should be null. The filename can be overriden by  the  environment  variable  RELAYCLIENTS. Addresses in relayclients may be wildcarded (2nd line in the example below):  192.168.0.1:  192.168.1.: Using MySQL relay table Run the command /var/indimail/bin/clearopensmtp in the cron every 30 Minutes By default every time who uses IndiMail's  POP3 or IMAP service and authenticates, the following happens: On successful authentication, IMAP/POP3 daemon inserts entry into relay table, inserting email, IP address and timestamp. If CHECKRELAY environment variable is enabled, SMTP checks the relay table for a entry within minutes specified by the RELAY_CLEAR_MINUTES environment variable. If the entry is there, RELAYCLIENT environment variable is set, which allows relaying. At this point, the SMTP server will allow that IP to relay for 60 Mins (default) clearopensmtp will clear all IP which have not authenticated in the past RELAY_CLEAR_MINUTES. clearopensmtp should be enabled in cron to run every 30 minutes. Set up Authenticated SMTP IndiMail also provides you authenticated SMTP providing AUTH PLAIN, AUTH LOGIN and AUTH CRAM-MD5 methods. Whenever a user successfully authenticates through SMTP, the RELAYCLIENT environment variable gets set. qmail-smtpd uses the RELAYCLIENT environment variable to allow relaying. Most of the email clients like thunderbird, evolution, outlook, outlook express have options to use authenticated SMTP. For a tutorial on authenticated SMTP, you can refer tohttp://indimail.blogspot.com/2010/03/authenticated-smtp-tutorial.html Using control file relaydomains Host  and  domain  names  allowed  to  relay mail through this host.  Each  address should be followed by a colon and an (optional) string that should be  appended  to  each incoming recipient address, just as with the RELAYCLIENT environment variable.  Nearly always, the optional string should be null. Addresses in relaydomains may be wildcarded:   heaven.af.mil:   .heaven.af.mil: Using control file relaymailfrom envelope  senders (MAIL FROM) listed in this file will be allowed to relay independently of the RELAYCLIENT environment variable. Entries in  relaymailfrom  can  be  E-Mail addresses, or just the domain (with the @ sign). Unlike relaydomains native addresses should be entered.  A line in  relay mailfrom  may be of the form @host, meaning every address at host.  relaymailfrom can also be in cdb format. If relaymailfrom.cdb  is  present,  it will be searched first. Examples:                [email protected]                @domain2.com If you use the control file /var/indimail/control/relaymailfrom, you should really know what you are doing. Any mail from having a domain component of the address matching any domain in this file, relaying will be allowed without any authentication. You can most probably use this only if you have a closed SMTP server to which access from outside is not possible. [Less]

A SMTP server is responsible for accepting mails from a sender and processing it for delivery to one or more recipients. In most situations, for domains which are under your administrative control (native addresses), the SMTP server should accept ... [More] mails without authentication. However, when a mail is submitted for delivery to domains which are not under your administrative control, you should accept mails only after it satisfies security considerations like having the sender authenticate itself. This is to prevent abuse of external domains using your SMTP server. A SMTP server which accepts mails for external domains without any authentication is called an open relay. The act of accepting mails for external domains for delivery is called relaying.The default configuration of IndiMail configures the SMTP as a closed system. Hence to be able to send mails to external domains, you need to setup mechanisms for relaying.There are many methods. Choose any of the below after studying them. I prefer 3 or 4 for security reasons.Have Sender's IP addresses in tcp.smtp fileUse control file relayclients for IP addresses of clients allowed to relay mail through this host.Configure IndiMail to use MySQL relay table (good security). This is implemented on POP3/IMAP before SMTPUse authenticated SMTP (good security)For allowing relay to specific domains use control file relaydomainsFor allowing specific users (native addresses) use control file relaymailfromNOTE: you should use 1 & 2 only if if the host having the sender's IP is under your control and you have good security policies for the host (however what is a good security can be very subjective)Using tcp.smtpYour startup script for the qmail smtp server must use the tcpserver -x file option similar to this startup line.env - PATH="/var/indimail/bin" tcpserver -H -R -x /var/indimail/etc/tcp.smtp.cdb \-c 20 -u 555 -g 555 0 smtp /var/indimail/bin/qmail-smtpd 2>&1IndiMail uses -x option to tcpserver and hence you need not bother about the above line. You however need to edit /var/indimail/etc/tcp.smtp and put in lines for all static IP's that you will always want to relay access to.127.0.0.:allow,RELAYCLIENT=””10.1.1.:allow,RELAYCLIENT=””The above lines will cause RELAYCLIENT environment variable to be set for localhost and all machines on the 10.1.1 class and hence allow to relay through. Remember that any user on hosts on 10.1.1 class will be able to relay mails. You many not want this. The line having 127.0.0. will allow any client on the IndiMail host to use SMTP and relay mails.If you add any IP to tcp.smtp, you have to rebuild a cdb database tcp.smtp.cdb. You can run the following command% sudo /var/indimail/bin/qmailctl cdbNOTE: Remember that you are exposed to unrestricted relaying from any of the IP addresses listed in tcp.smtpUsing control file relayclientsIP addresses of clients allowed to relay mail  through  this  host.   Each address should be followed by a colon and an (optional) string that should be appended to each incoming recipient address, just as  with  the  RELAYCLIENT environment variable.  Nearly always, the optional string should be null. The filename can be overriden by  the  environment  variable  RELAYCLIENTS.Addresses in relayclients may be wildcarded (2nd line in the example below): 192.168.0.1: 192.168.1.:Using MySQL relay tableRun the command /var/indimail/bin/clearopensmtp in the cron every 30 MinutesBy default every time who uses IndiMail's  POP3 or IMAP service and authenticates, the following happens:On successful authentication, IMAP/POP3 daemon inserts entry into relay table, inserting email, IP address and timestamp.If CHECKRELAY environment variable is enabled, SMTP checks the relay table for a entry within minutes specified by the RELAY_CLEAR_MINUTES environment variable. If the entry is there, RELAYCLIENT environment variable is set, which allows relaying. At this point, the SMTP server will allow that IP to relay for 60 Mins (default)clearopensmtp will clear all IP which have not authenticated in the past RELAY_CLEAR_MINUTES. clearopensmtp should be enabled in cron to run every 30 minutes.Set up Authenticated SMTPIndiMail also provides you authenticated SMTP providing AUTH PLAIN, AUTH LOGIN and AUTH CRAM-MD5 methods. Whenever a user successfully authenticates through SMTP, the RELAYCLIENT environment variable gets set. qmail-smtpd uses the RELAYCLIENT environment variable to allow relaying.Most of the email clients like thunderbird, evolution, outlook, outlook express have options to use authenticated SMTP.For a tutorial on authenticated SMTP, you can refer tohttp://indimail.blogspot.com/2010/03/authenticated-smtp-tutorial.htmlUsing control file relaydomainsHost  and  domain  names  allowed  to  relay mail through this host.  Each  address should be followed by a colon and an (optional) string that should be  appended  to  each incoming recipient address, just as with the RELAY\CLIENT environment variable.  Nearly always, the optional string should be null. Addresses in relaydomains may be wildcarded:  heaven.af.mil:  .heaven.af.mil:Using control file relaymailfromenvelope  senders (MAIL FROM) listed in this file will be allowed to relay independently of the RELAYCLIENT environment variable. Entries in relaymailfrom can be E-Mail addresses, or just the domain (with the @ sign).Unlike relaydomains native addresses should be entered.  A line in  relay mailfrom  may be of the form @host, meaning every address at host.  relaymailfrom can also be in cdb format. If relaymailfrom.cdb  is  present,  it will be searched first.Examples:  [email protected]  @domain2.comIf you use the control file /var/indimail/control/relaymailfrom, you should really know what you are doing. Any mail from having a domain component of the address matching any domain in this file, relaying will be allowed without any authentication. You can most probably use this only if you have a closed SMTP server to which access from outside is not possible. [Less]