The art of setting up a sendmail server on Debian 8

But why? Fact number one: Running your own mail server is the most likely cause for messing up, and that can mean an intrusion to the server or just turning it into a public toilet for spam. Nevertheless, if mail delivery is important to you, there’s probably no way around. And I’m not talking about [...]

Gmail: How to turn off spam filter for incoming mails

Gmail is definitely the leader in the field of email services, and their spam filter is actually very good. From my own experience with setting up a mail server, I can tell that it’s not all that easy to make Gmail’s incoming mail servers even talk with you. So the larger part of spammer don’t [...]

The SPF, DKIM and DMARC trio: Making your email appear decent

Intro Whether you just want your non-Gmail personal email to get through, or you have a website that produces transactional emails (those sent by your site or web app), there’s a long fight with spam filters ahead. The war against unsolicited emails will probably go on as long as email is used, and it’s an [...]

SMTP tidbits for the to-be postmaster

This is a quick overview of the parts of an SMTP session that are relevant to SPF and mail server setup. Just a sample SMTP session For a starter, this is what an ESMTP session between two mail servers talking on port 25 can look like (shamelessly copied from this post, which also shows how [...]

fetchmail, openssl and a sudden failure to authenticate certificates

Since around the beginning of December 2017, fetchmail stopped retrieving mails form Gmail servers silently, without issuing any kind of error message. Only when starting fetchmail in the foreground, I got fetchmail: Server certificate verification error: unable to get local issuer certificate fetchmail: This means that the root signing certificate (issued for /C=US/O=Google Trust Services/CN=Google [...]

Outgoing SMTP mail servers considerations

Mail with gmail.com as From address vanishing It started really bad: Someone asked me why he hasn’t received an answer from me in two weeks, and I had answered his mail the same day I got his. It turned out that Gmail had thrown mail into the black hole without any warning. Probably the updated [...]

Using a shell account as a manual sendmail relay

So the situation is like this: An email I attempted to send got rejected by the recipient’s mail server because my ISP (Netvision) has a poor spam reputation. And it so happens that I have a shell account (with root, possibly) on a server with an excellent reputation. So how do I use this advantage? [...]

Plain-text mail from Thunderbird (under Linux)

Introduction I’ve been annoyed for quite a while by Thunderbird’s strong inclination towards HTML mail. To the extent that if I don’t really, really verify that a mail goes out in plain text, it’s probably going to slip out in HTML. This is bad in particular when sending mails to Linux-related mailing lists. They don’t [...]

A perl script sending mails for testing a mail server

Just set up your mail server? Congratulations! Now you should test it. In particular, check if it relays mails to other servers and if the response time is reasonable. Here’s a script for doing the testing. Just edit the arguments to send_mail() to match your setting. #!/usr/bin/perl use warnings; use strict; use Net::SMTP; send_mail(’127.0.0.1′, # [...]

Setting up a VPS server. It was a bumpy road.

Introduction These are my own notes as I set up an OpenVZ VPS server, based upon CentOS 5.6 to function as a web and mailing list server. A $36/year 128 MB RAM machine was good enough for this. Since there’s some criticism about the hosting provider, and it looks like they’re OK after all, I’m [...]