E-mailed addressed to numbered username

[Rob Myroon <ro...@tartan.ca>]

Hi,

I get a lot of e-mail where the username contains only numbers.

ex.
50502@tartan.ca
5080507@tartan.ca
7030303@tartan.ca

These users don't exist so postfix simply throws the e-mail away but I 
am curious if anyone knows why spammers bother to send all these 
e-mails? Are they checking to see if I have a mail server running?

Thanks,
Rob

RE: E-mailed addressed to numbered username

[Giampaolo Tomassoni <g....@libero.it>]

From: Rob Myroon [mailto:rob.myroon@tartan.ca]
> 
> Hi,
> 
> I get a lot of e-mail where the username contains only numbers.
> 
> ex.
> 50502@tartan.ca
> 5080507@tartan.ca
> 7030303@tartan.ca
> 
> These users don't exist so postfix simply throws the e-mail away but I 
> am curious if anyone knows why spammers bother to send all these 
> e-mails? Are they checking to see if I have a mail server running?

FWIK, some (often large) e-mail service providers do create custom mailbox and accounts with just the account id, then they assign the customer-wanted name aliasing that mailbox.

Also, in some cases and some (quaint) MTA's, a mailbox may be identified by its uid.

Since uids and mailbox's numeric ids are often assigned sequentially, this kind of scavenging approach has the advantage that when a mailbox if finally found, all the others are just numbers following the same pattern.

I.e.: suppose you can send a mail to 10051@domain.tld. You may easily bet that you'l find mailboxes on every id starting from, say, 10000 up to the first delivery error.


> Thanks,
> Rob

You welcome,

g