Are you wondering what to do when SMTP does not work with IPv6 on Digital Ocean? Our DigitalOcean Support team is here to lend a hand with your queries and issues.

SMTP does not work with IPv6 on Digital Ocean

If SMTP does not work with IPv6 on Digital Ocean, you have come to the right place. This particular issue is often accompanied by the following symptoms:

• Emails are not delivered when we use Plesk on DigitalOcean.
• The DigitalOcean server has enabled IPv6, and IPv4 addresses as well as Postfix.
• The ip6tables and Plesk firewall configuration allows outgoing traffic through IPv6:

  ACCEPT tcp ::/0 ::/0 tcp dpt:25
• The records in /var/log/maillog time out.
• A warning may appear after the Daily maintenance task is executed in Mail Server Settings under Tools & settings.

In case the SMTP traffic over IPv6 is blocked at the network level in DigitalOcean, our experts offer this fix. It involves editing the gai.conf file to prioritize IPv4 to modify the precedence over the getaddrinfo calls. This is done by connecting to the server through SSH and proceeding with these steps:

For RHEL/CentOS:

1. First, we have to create the file /etc/gai.conf.
2. Then, add the following line to the file:

   precedence ::ffff:0:0/96 100
3. Now, save the file and exit.

For Debian/Ubuntu:

1. First, open the /etc/gai.conf file with a text editor.
2. Then, remove the comment symbol (#) from the line below:

   CONFIG_TEXT:# precedence ::ffff:0:0/96 100
3. Then save the file and exit.

Let us know in the comments if this quick fix helped you resolve this error.

[Need assistance with a different issue? Our team is available 24/7.]

Conclusion

In conclusion, our Support Engineers demonstrated how to proceed if SMTP does not work with IPv6 on Digital Ocean. We also got a look at the different ways this error presents itself.