I can't send mail to Gmail addresses

Savalet

Hello, I installed a mailcow server with docker and when I send an email to a gmail email address I never receive it and I have this error in the postfix logs.

DaLLLi

I have no problem sending messages to gmail or outlook.

Check the server’s IP for blacklist.
Check the DKIM and SPF keys.
Use encrypted connections - ports 465, 993
Domains xyz and similar are often blocked by default.
If the domain is new, you need to build its reputation. It takes time.

Savalet

Thank you for your answer but how can I use port 465 or 587 to send mail on mailcox? And for more precision I tested to send emails to addresses: gmail.com, outlook.com, yopmail.com, mailausor.com and none worked with the same error so I don’t think it’s is a blacklist or other but really my mail server which cannot send mail on another domain than its own

DaLLLi

Just install Thunderbird and set it up for your account.
Set ports 465 and 993. Full SSL, not STARTTLS. Check if it works.
https://mailcow.github.io/mailcow-dockerized-docs/client/client-thunderbird/

Although the messages are rather about the lack of connection to the server. Looks like a blacklist …

Savalet

And for SOGo ?

DaLLLi

SOGO does not have this configuration.
Log in to the admin panel and edit your mailbox. Force encrypted connections.
It doesn’t necessarily help.🤷‍♂️

Savalet

I have test on thuderbird with 465 port and it’s not work :

DaLLLi

Maybe try this tool.
https://dnschecker.org/smtp-test-tool.php
Generate a temporary password with only SMTP authorizations in the mailbox administration panel.
Try port 25, 465, 587