Cannot send email from dockerized mailcow

marqrdt

Hi everyone,
I’m enjoying mailcow-dockerized and can receive emails for my domain, but cannot seem to send any emails to any external provider. I’m running Mailcow on a RaspberryPi 5 inside of my home network. I have ports forwarded and can receive emails. A few things about my setup:

I can receive emails just fine
My ISP address resolves to an address with Sparklight: 96-18-233-53.cpe.sparklight.net.
I seem to have the proper DKIM and DMARC records according to mxtoolbox.com:
https://mxtoolbox.com/SuperTool.aspx?action=dkim%3ausrtech.com%3aemail&run=toolpage#
https://mxtoolbox.com/SuperTool.aspx?action=dkim%3ausrtech.com%3aemail&run=toolpage#

A few things I’ve noticed:
Most emails show in my mail queue like this:
This is the mail system at host mail.usrtech.com.

####################################################################

THIS IS A WARNING ONLY. YOU DO NOT NEED TO RESEND YOUR MESSAGE.

####################################################################

Your message could not be delivered for more than 4 hour(s).
It will be retried until it is 5 day(s) old.
…
test-ailtwsb6o@srv1.mail-tester.com: connect to
reception.mail-tester.com[94.23.206.89]:25: Connection timed out

==========================================

Similar when I send to one of my Gmail accounts:
paulrm1234@gmail.com: connect to
alt2.gmail-smtp-in.l.google.com[142.250.152.27]:25: Connection timed out

==========================================

From the host RaspberryPi running mailcow-dockerized, I can’t seem to connect to any of the know SMTP ports on the target system, for example:
me@mypi:~ $ nc alt2.gmail-smtp-in.l.google.com 587

With the exception of Outlook:
me@mypi:~ $ nc outlook.com 587
220 BN0PR07CA0003.outlook.office365.com Microsoft ESMTP MAIL Service ready at Thu, 28 Nov 2024 22:25:21 +0000 [08DD0F4262701347]

I did send an email to my Outlook.com account but it never showed up in my Inbox or Spam folder.
Any ideas would be much appreciated.

Cheers and Happy Thanksgiving to all who celebrate,
Paul M

mlcwuser

marqrdt

Regardless of any block list entries, you are already in trouble because the reverse DNS record does not match your mail server’s SMTP banner, which should point to mail.usertech.com instead of 96-18-233-53.cpe.sparklight.net, and this can only be changed by your ISP.

Long story short, talk to your ISP if you really need to send email directly from your home network.

The requirements are

a static IP address (your ISP may be able to provide this, possibly for an extra charge)
correct reverse DNS (PTR) record (your ISP will have to do this for you)
removal from blocking lists if the IP assigned to you by your ISP is on any (your ISP may be able to do this for you, or you may have to do it yourself, but only after requirements 1 and 2 are met).

pkernstock

Error is “Connection timed out”, so maybe your hoster is blocking TCP/25?

DocFraggle

As we already discussed countless times, don’t use your mailcow to send mails directly at home, as most if not all ISP IP ranges are found on blacklists.
Use a relay service like mailgun for this

marqrdt

Thank you – knowing that I might end up just wasting my time trying to get it to work is very helpful. I used to have a VPS Linux server with Bluehost but didn’t want to spend the $$$ to keep it running. I can handle the web-hosting piece myself probably, but as you pointed out, running a mail server requires much more cooperation from the folks in charge of DNS for their network. My IP address has been stable – has not changed in about a year– but technically it’s not static. I basically just update my DNS records (register.com) and live with a short outage for a few hours.

esackbauer

I am running my private mailcow on a home connection since years without a problem.
However I know exactly what I am doing 😉
I use ddns-updater to update DNS A records when my ISP assigns me a new one (same here, usually they last for 1 year on my cable network, but will happen sooner if they need to move things around)
Sending mails I do with a relay server hosted at a friends static IP range.