Can't send email to Gmail

IskandarAlex2

I have set up my Mailcow with all the necessary DNS records and rDNS for receiving and sending. I can receive emails from Gmail without any issue, but the problem arises when sending to Gmail. This is the postfix log

1C0B914F72C1: to=<myemailaddress@gmail.com>, relay=none, delay=97696, delays=97546/0.02/150/0, dsn=4.4.1, status=deferred (connect to alt2.gmail-smtp-in.l.google.com[142.250.150.26]:25: Connection timed out)

So far, I know Google SMTP doesn’t accept at port 25, and I tried myself with telnet which it stuck on trying and just timeout. However, I tried the other ports, like 465 and 587, which both connected with no problem at all. I am still new to Mailcow, so I have no idea how to tell Mailcow to use those SMTPS ports.

ETNyx

It seem that you have some firewall on the way, that is blocking regular traffic on port 25, make sure your firewalls are correctly set-up and ask your ISP if he is blocking and/or allow you to use this port.

DocFraggle

Most hosting providers block port 25 outgoing nowadays to get rid of SPAMmers. Hetzner for example opens port 25 only for customers who paid the first bill after 30 days

IskandarAlex2

I contacted my VPS to unblock it, and it works now. Thanks.