As SPAM evolves the techniques used change over time, it is because of this that mail servers running the very popular “Spamassassin” software should keep it up to date.

If you’re receiving a lot of spam, don’t delete them… Move it all into a “Spam” directory in your IMAP account so that we can use them to enlighten the anti spam software.

In order to teach Spamassassin first we need to introduce it to the spam you’ve stored:

$ sa-learn -u exim --dbpath ~exim/.spamassassin/ --spam [MAILDIR CONTAINING SPAM]

Now delete all this SPAM from your mailbox.

Finally we should also show Spamassassin what valid email looks like, by knowing these two it will be able to make a more “informed” decision on whether a message is SPAM or HAM.

$ sa-learn -u exim --dbpath ~exim/.spamassassin/ --ham [MAILDIR CONTAINING VALID MAIL]

To resolve this issue I’ve implemented SPF (sender policy framework) which will verify that the email being sent is from a trusted server (being either my webmail server, home or office).

If you’re able to manage the DNS records for your domain you can add the following “TXT” record for “@”:

v=spf1 a mx ip4:x.x.x.x ~all

Where x.x.x.x is your mail server, web server, etc, etc. You can add multiple IP addresses by simply adding another “ip4: y.y.y.y”.

v=spf1 a mx ip4:x.x.x.x ip4:y.y.y.y ~all

Example:

v=spf1 a mx ip4:82.71.110.139 ip4:217.112.87.134 ~all