Relay per Domain

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Relay per Domain

 - This article is a Work in Progress, and may be unfinished or missing sections.

Reference bugs: http://bugzilla.zimbra.com/show_bug.cgi?id=32740 and https://bugzilla.zimbra.com/show_bug.cgi?id=95348

Zimbra allows relaying emails to a specific server only, i.e using zimbraMtaRelayHost. However, there are needs to relay emails per domain basis based on the sender. For example, you want emails sent by users@domain1.com should be relayed through smtp.domain1.com and users@domain2.com through smtp.domain2.com servers. You can configure it using postfix's "sender_dependent_relayhost_maps".

This is an example that has been tested on ZCS 5.0.16 and ZCS 7.1.4

Note: Below settings will not survive zimbra upgrades. Make sure you take backup of config files before upgrading.

1. Add following line to /opt/zimbra/postfix/conf/main.cf

Pre 8.5:
sender_dependent_relayhost_maps = hash:/opt/zimbra/postfix/conf/bysender
8.5:
sender_dependent_relayhost_maps = lmdb:/opt/zimbra/postfix/conf/bysender

2. Create file /opt/zimbra/postfix/conf/bysender and enter your domain names and relay server's IP addresses.

@domain1.com  [10.10.10.1]
@domain2.com  [20.20.20.1]

You can even add individual email IDs to relay their emails to specific relay host.

 user@domain.com [10.10.10.2]

3. Create the hash file.

postmap /opt/zimbra/postfix/conf/bysender

4. Restart zmmtactl

zmmtactl stop
zmmtactl start

5. Test by sending emails.

ZCS 8.7 instructions

1. Open /opt/zimbra/common/conf/main.cf.default file for editing with your favorite editor (e.g. vi).

2 . Find the sender_dependent_relayhost_maps parameter and set it to be lmdb:/opt/zimbra/postfix/conf/bysender

sender_dependent_relayhost_maps = lmdb:/opt/zimbra/postfix/conf/bysender

Description:

sender_dependent_relayhost_maps (default: empty)
A sender-dependent override for the global relayhost parameter setting.The tables are searched by the envelope sender address and @domain. 

3.Create a file /opt/zimbra/common/conf/bysender and enter your domain names and relay server's IP addresses.

@domain1.com  [10.10.10.1]
user@domain2.com  [20.20.20.1]

4. Create the hash file.

postmap /opt/zimbra/common/conf/bysender 

5.

zmmtactl stop; zmmtactl start