The Boston Diaries

The ongoing saga of a programmer who doesn't live in Boston, nor does he even like Boston, but yet named his weblog/journal “The Boston Diaries.”

Go figure.

Sunday, January 16, 2022

A most persistent spam, part VI

It seems that “Aleksandr” may have changed his name to “Mayboroda,” but it looks like it's the same type of weird spam I've since blocked successfully. Only here, reader Roberto found a way to block the spam for users of Postfix (and I did get Roberto's permission to post this email):

From
Robysampler <XXXXX­XXXXX­XXXXX­XXXXX­X>
To
sean@conman.org
Subject
About "Mayboroda_aleks" on your personal blog
Date
Sun, 16 Jan 2022 23:04:07 +0100

Dear Mr. Sean

My name is Roberto from Italy.

i've read your personal blog about the mayboroda aleks spammer, who's bothering me, filling my own company email since one and half years, at least.

as you figured out "Mayboroda", keeps changing IPs and domain/subdomains to evade every try to block him.

luckly, my company mail is served by a linux machine i own, so i have direct access to it, and as final solution i've choose to do some fine tuning in postfix config.

i've add inside postfix "main.cf" file:

smtpd_recipient_restrictions = check_sender_access regexp:/etc/postfix/rejected.senders

then i've add in "rejected.senders":

/s[0-9]{1,2}.[a-z].ru/ REJECT
/info@.[a-z].ru/ REJECT

in this case you'll provide to your postfix daemon, some rejecting rules based on regular expressions.

based on hundreds of mails "Mayboroda" has sent me, i figured out the main pattern for his emails usually are

info@randomdomain.ru

or

something@s(1 or 2 numbers).randomdomain.ru

after setting up your postfix you can check out the result using the command

postmap -q "your test email here" regexp:/etc/postfix/rejected.senders

for example

postmap -q "info@s4.mayboroda.ru" regexp:/etc/postfix/rejected.senders

the shell returns REJECT

this will works until "Mayboroda" will continue to use the same pattern in the mail sender

I hope you'll appreciate my advices.

have a nice day and happy new year

Roberto

Best Regards

I do appreciate your advice, Roberto. Thank you. I'm sure other people will find this useful as well.

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