Restrict Users to send mail to certain domain in zimbra

In zimbra mailserver you can restrict/allow user to send mail with local user using smtpd_sender_restrictions.
Here is steps of this setup follow the below article

Login to Zimbra User
# su – zimbra
$ cd /opt/zimbra/conf

[zimbra@mail conf]$ echo "user@example.com restrict_tpmail" > tpmail_senders

$cat tpmail_senders
user@example.com restrict_tpmail

Update file
[zimbra@mail conf]$ postmap tpmail_senders

Note: You can add users in this file tpmail_senders who you want to restrict and update.

[zimbra@mail conf]$ cd /opt/zimbra/conf

Find/Get Available domain name

[zimbra@mail conf]$ zmprov -l gad
example.com

[zimbra@mail conf]$ echo  "example.com OK" > tpmail_recipients

Update file
[zimbra@mail conf]$ postmap tpmail_recipients
[zimbra@mail conf]$ cat tpmail_recipients
example.com OK

Note : You can allow more than one domains (xyz.com) in this file tpmail_recipients

Add higlighted/Bold line in file smtpd_sender_restrictions
[zimbra@mail conf]$ vim /opt/zimbra/conf/zmconfigd/smtpd_sender_restrictions.cf
%%exact VAR:zimbraMtaSmtpdSenderRestrictions reject_authenticated_sender_login_mismatch%%
%%contains VAR:zimbraServiceEnabled cbpolicyd^ check_policy_service inet:localhost:%%zimbraCBPolicydBindPort%%%%
%%contains VAR:zimbraServiceEnabled amavis^ check_sender_access regexp:/opt/zimbra/postfix/conf/tag_as_originating.re%%
check_sender_access texthash:/opt/zimbra/conf/tpmail_senders
permit_mynetworks, reject_sender_login_mismatch
permit_sasl_authenticated
permit_tls_clientcerts
%%contains VAR:zimbraServiceEnabled amavis^ check_sender_access regexp:/opt/zimbra/postfix/conf/tag_as_foreign.re%%

Go to the Postfix config file and add below parameter 

[zimbra@mail conf]$ vim /opt/zimbra/postfix/conf/main.cf
smtpd_restriction_classes = restrict_tpmail
restrict_tpmail = check_recipient_access texthash:/opt/zimbra/conf/tpmail_recipients, reject

Restart service
[zimbra@mail conf]$ zmmtactl restart
[zimbra@mail conf]$ postfix reload

Note: this document is tested in Zimbra 8.5, 8.6, 8.7

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About Penguin Technology

I am a passionate cloud and DevOps professional specializing in Linux and open-source solutions. Through this blog, I share my knowledge and experience with the community, offering tips and insights on cloud technologies and DevOps practices.