autoconfig returns mailcow_hostname for all domains, causing security certificate errors with Outlook clients

[ibesec]

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Description

As per default, autoconfig returns mailcow_hostname for all hostname fields (incoming server/IMAP, outgoing server/SMTP, etc.), even for secondary domains.

This results in Outlook client returning an Internet Security Warning:
"The server you are connected to is using a security certificate that cannot be verified -  The target principal name is incorrect."

Returning the secondary domain's hostname instead fixes this issue.

Logs:

N/A

Steps to reproduce:

1. Set up a mailcow instance with an extra SAN (will call this the "secondary domain"), and set up all advanced SSL configurations as required.
2. Verify the newly issued Let's Encrypt certificate now includes your secondary domain as a SAN.
3. Create a new mailbox in the secondary domain.
4. Add your new mailbox as a new account to any Outlook (classic) client using the autoconfig parameters - don't manually modify any hostnames or ports.
5. The Internet Security Warning message will pop up.
6. By editing the newly added account details in Outlook, you will confirm autoconfig set IMAP and SMTP hostnames to the main mailcow_hostname.
7. Change the IMAP and SMTP hostnames to the secondary domain.
8. You have fixed the issue.

Which branch are you using?

master

Which architecture are you using?

x86

Operating System:

N/A

Server/VM specifications:

N/A

Is Apparmor, SELinux or similar active?

N/A

Virtualization technology:

N/A

Docker version:

N/A

docker-compose version or docker compose version:

N/A

mailcow version:

2024-11b

Reverse proxy:

N/A

Logs of git diff:

N/A - only changes to SOGo configuration and certificates.

Logs of iptables -L -vn:

N/A

Logs of ip6tables -L -vn:

N/A

Logs of iptables -L -vn -t nat:

N/A

Logs of ip6tables -L -vn -t nat:

N/A

DNS check:

N/A