Outgoing SMTP connection issues


#1

Hi, I am trying to setup some services that need to connect to an external smtp server and I just keep getting timeouts while connecting any port (25, 465, 587…) with STARTTLS or TLS, by domain, direct ipv4 or direct ipv6 (telneting to the smtp server also timeouts). Logs on the SMTP server-side don’t show any connection attempt so the trouble is most likely somewhere in between the scaleway machine and the smtp server. This behavior is consistent between multiple external smtp servers (that I can connect to without problems from non-scaleway machines). I am running centos7 (with firewalld so there is absolutely no outgoing firewall filter) on a VC1L.

I cannot find any clue about this kind of failure anywhere (I read about some trouble with the scaleway nat or with smtp over ipv6 but nothing really more) so I can’t get any further. Any ideas?


#2

Hi lapinot,
I had the same issue a while ago, and found that this is documented on the FAQ: https://www.scaleway.com/faq/server/network/#-I-cannot-send-any-email . Note that the documentation doesn’t tell explicitly that you have to make an hard reboot (from the control panel), and not just a soft reboot (i.e. running the “reboot” or “shutdown” commands).

Hope this helps


#3

Thanks a lot! This feature is absolutely insane, it’s incredible, I don’t even know why it exists.


#4

Blocking outgoing SMTP unless the owner of the server explicitly requests access is a common practice with cloud and VPS platforms. With shared platforms like these, someone sending spam can have a huge knock-on impact on everyone else if an IP range is blacklisted.

By blocking outgoing SMTP by default, a badly secured server hacked by someone cannot then be used as a spam bot or relay.


#5

Mmh, it makes sense. It’s weird that I never encountered such a thing.