A long time ago, saint IGNUcius helped me to realize that Google is literally the worst thing humanity has ever created right after League of Legends, so I embarked on a quest to completely free myself from depending on big tech and proprietary software overall. My heroic tale came to an end when I encountered the final boss of self hosting: E-mail. Setting up SQL, MTA, MDA and the likes was really tedious. After I finally managed to somehow glue the components together, my spirit was totally broken by the fact that most ISPs including mine block the e-mail port 25 uplink to “avert spam”.
Years later I discovered mailu and set up my e-mail server in 15 minutes (gg ez). The setup tool provided in the documentation was a major W.
But how did I send mail when port 25 uplink was blocked?
Configuring SMTP relay
My ISP (Elisa, Finland) actually allowed uplink traffic on port 25 if and only if it was for their SMTP server. No authentication was required as long as the sender’s IP was in their address space. Configuring this to mailu required editing only one line in mailu.env:
# Will relay all outgoing mails if configured
RELAYHOST=smtp.kolumbus.fi:25
Finally, no Google.