ISPmail Buster

Quotas

Now this is a feature that caused me quite some headache. But in the end it was pretty simple. Quotas are size limits for users. You can make sure that users do not waste infinite amounts of disk space but are forced to clean up old emails every now and then. The magic happens in …

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Success stories

I would appreciate if you leave a comment here telling others if your mail server is running. Perhaps even a word about the purpose of the mail server and the number of users you have. That allows others to see that their time is well-spent and indeed leads to a working mail server. Thanks for …

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Blocking malware

My usual rant: I consider virus scanners snake oil. If anyone wants to seriously infect a computer by sending an infected attachment then virus scanners won’t help you. They are based on patterns of known malware and (if you are lucky) a working heuristic algorithm trying to detect unusual behavior. It has been proven time and …

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Monitoring and backup

You have come a long way. Glad you made it. So many weird things complicated the journey that evolved from the very beginning of using email roughly 35 years ago. But before you take your much deserved break from these adventures let’s take care of some final tasks. Monitoring For me there is nothing more …

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Prevent spoofing using DKIM

Email sender spoofing is the act of pretending to be in control of someone else’s email address. This is a common problem with phishing. Often scammers send emails with a sender address of something@paypal.com and hope that the recipient falls for it and trusts them. In fact SMTP does not care which sender address you …

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Mail client auto-configuration

Have you ever worked with Thunderbird as a mail client? When you add a mail account you get a wizard like this: You click on Continue and Thunderbird tries to find out which parameters are needed to connect to your mail server properly. But usually you just end up with this: What is necessary to …

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DNS records

MX entries So now you have your working mail server. But how do other mail servers get to know you? The answer lies in the most important service on the internet: DNS. Assume that a mail server somewhere on the other end of the internet wants to send an email to john@example.org. The server must …

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