I can send e-mails, but not receive them

Culottes

Hello,

I installed MailCow Docker on my VPS, the installation worked well, but after testing, I noticed that I could not receive mail. But I can send them

I normally followed the tutorial, but I don’t know if I made a configuration error. Here is the domain of my mail server “mail.sagbot.com” to receive mails with the domain “exemple@sagbot.com”. Of course, I’ve registered an MX record in my DNS.

Best regards,
Culottes

piperino

Culottes
Port 25 is not available from the intern to your server.

Culottes

But I don’t understand, I’ve authorized port 25.

Culottes

Especially since I don’t see how port 25 would prevent mail reception.

piperino

Culottes

over which port do you expect your MTA is receiving mails?
no offense, but it looks like you don’t understand the basics of SMTP.

DocFraggle

Well, mail servers send email to your server on port 25 (that’s the port postfix is listening), which isn’t reachable at your mail server

https://mxtoolbox.com/SuperTool.aspx?action=smtp%3Amail.sagbot.com&run=toolpage

Again, check your local firewall, or maybe you have an additional firewall available at your VM hoster like my Hetzner cloud firewall which is still blocking this and maybe other ports

Culottes

Yes, my mistake, mail server to mail server, they use port 25. But that doesn’t change the fact that I don’t have a firewall blocking it and my ISP doesn’t block it.

piperino

run a
netstat -an | grep “:25”

from the server console. just to be sure port 25 is even listening.

an nmap to your machine shows following ports are open but 25
PORT STATE SERVICE
21/tcp open ftp
22/tcp open ssh
80/tcp open http
110/tcp open pop3
143/tcp open imap
443/tcp open https
465/tcp open smtps
587/tcp open submission
993/tcp open imaps
995/tcp open pop3s
3000/tcp open ppp
8010/tcp open xmpp
8080/tcp open http-proxy
8443/tcp closed https-alt

Culottes

Yes, I understand that the port isn’t open, but my firewall hasn’t blocked it, it even says it’s open.

DocFraggle

Dumb question, but did you already restart your mailcow?

docker compose down
docker compose up -d

Culottes

Yes, I even tried to reboot my VPS and ufw

DocFraggle

What’s the log output of your postfix container after restarting? There must be something in it why it can’t bind to port 25

Culottes

I have this

I tried to remove the “SPAMHAUS_DQS_KEY=” value in my “mailcow.conf”. But still nothing, even though I no longer have the error in my logs.

DocFraggle

Ok, please check your mailcow.conf if you accidentally use this strange string in another line of the config

Btw, this DQS string is far too long

Culottes

Now i have this, without SPAMHAUS_DQS_KEY

DocFraggle

OK, looks like it’s running now:

https://mxtoolbox.com/SuperTool.aspx?action=smtp%3Amail.sagbot.com&run=toolpage

Culottes

It finally works, after deactivating it:

What exactly are these settings for?

Aditya-Rajgor

Thanks for sharing, yep, removing relay option worked for me as well.