It's a verification service, or a spammer doing the same.
They're testing your server's response to an address which is guaranteed
to not exist. End goal is to find catch-all domains, and to confirm the
rejection message given on a non-existent address.
On 27/5/25 10:08, J Doe via mailop wrote:
Hi,
I operate a small mail server for a non-profit organization. Over the
last two weeks or so, I have observed servers connecting and attempting
to deliver to non-existent addresses.
Ordinarily it's pretty easy to figure out what's going on ... they are
approximations of accounts such as: first-initial-last-name@domain,
which I am assuming are e-mail list validation services or possibly
people attempting to deliver to a mistyped account name, but now I am
seeing delivery attempts for a seemingly random list of alphanumeric
characters - for example, something like: s8d2x1@domain.
Does anyone see deliver attempts like this ? No "ordinary" human
account would be a string of alphanumeric characters and while this
might be a list verification service with a bug, there seems to be a
fair number of attempts.
What could this be ?
Thanks,
- J
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