Send mail only using ipv4

Tipuvesi

Hi,

I want to send mail only using ipv4 and not ipv6 because I can only have a PTR record for ipv4.
Do I need to disable ipv6 altogether or is there a way to only disable the sending of emails via ipv6?

Thanks

ETNyx

Than you can try to disable ipv6, but be careful, there is a few peoples that have problem whit disabling ipv6, double check if you are not ipv6 open relay after your modification https://docs.mailcow.email/post_installation/firststeps-disable_ipv6/

another way should be to disable ipv6 on your host interface itself,..

Tipuvesi

Thanks

apio-sys

I don’t think you need to disable the entire IPv6 stack to do this. It’s dangerous and can have negative effects (probably Sieve won’t work anymore for instance). However, if you just want to make that your outgoing mail uses IPv4, you can edit or create data/conf/postfix/extra.cf and add the following lines:

smtp_address_preference = ipv4
smtp_bind_address = [your_ipv4_to_use_for_sending]

The restart the postfix container docker compose restart postfix-mailcow. Your ourgoing mail will now no longer use IPv6 but IPv6 remains enabled for all the rest.