On 2025-06-11 05:36, John Levine via mailop wrote:
Pro Tip: if you don't want to be treated as a spammer, don't act or look like
one.
Absolutely! start by not pointing a gun at recipients. After trying for
almost a month to get Mailgun's attention on a spamming operation
emanating from their servers, the best they could offer me was to put my
affected recipient address on a "suppression list," which practically
means they would prevent the spammer from spamming that one address, but
spamming would continue for the rest of the world. Not good enough.
I have asked them to uniquely identify sending accounts with some custom
header / token, to empower mailbox operators to filter that stream of
sewage and deal with it differently from the other, higher value streams
that are commingled in their stream. NO RESPONSE.
I blocked Mailgun. Details (for Postfix) below. The rejection message
gives away a few things:
(a) it tells the sender why I am blocking Mailgun;
(b) it also gives away to Mailgun the affected recipient address.
Best case, (a) shows up on the dashboard of the well behaved accounts
and those paying senders will put pressure on Mailgun to segregate their
legitimate mail stream from compromised sending accounts and other
sewage. If Mailgun does not do it, the customer will hopefully move
their (paid) business elsewhere. It is telling that Mailgun
themselves, in their communication with me, did not use their own,
commingled piping.
Worse case, (b) gives Mailgun the opportunity to add recipient addresses
to their "suppression list" and they can continue dumping sewage on
behalf of their spamming customer to other mailboxes. Not a good
outcome. Abuse deserves to be blocked as a general rule, not as an
exception to an excessively permissive general rule.
I still find this better than not providing discernible/actionable
feedback at all, even if Mailgun could use the information to feed the
suppression list and keep their spamming customer happy.
Current result on my end: spamming on the compromised recipient
addresses ended two weeks ago. Legitimate senders using Mailgun are
still blocked, and I am observing:
The blocked messages include some seriously high value communication:
voting notices from a corporate election service and notice service for
Canadian municipalities. Commingling such high value communication with
much lesser value communication, or outright spam, is negligent at best.
They also included legitimate (as in: desired by the recipient) bulk
mail, such as from a voip provider or from Costco.
And then they included some lowly businesses such as opportunistic
unsolicited financial disservices provider payme.io.
As a recipient, commingled traffic of various quality/value emanating
from the same infrastructure is treated the same; and that same
treatment is the lowest level. Senders be warned.
In Postfix's main.cf
smtpd_client_restrictions =
...
check_client_access cidr:/etc/postfix/block_spamgun
...
Content of /etc/postfix/block_spamgun
104.130.122.0/23 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
104.130.96.0/28 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
141.193.32.0/23 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
143.55.224.0/21 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
143.55.232.0/22 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
143.55.236.0/22 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
146.20.112.0/26 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
146.20.113.0/24 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
146.20.191.0/24 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
159.112.240.0/20 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
159.135.132.128/25 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
159.135.140.80/29 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
159.135.224.0/20 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
161.38.192.0/20 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
161.38.204.0/22 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
166.78.68.0/22 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
185.189.236.0/22 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
185.211.120.0/22 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
185.250.236.0/22 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
192.237.158.0/23 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
198.244.48.0/20 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
198.244.60.0/22 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
198.61.254.0/23 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
204.220.160.0/21 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
204.220.168.0/21 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
204.220.176.0/20 REJECT 454 5.7.1 Mailgun mingles your mail with
mail from spammers. Change Email Sending Provider, or ask Mailgun to
clean up.
209.61.151.0/24 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
23.253.182.0/23 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
69.72.32.0/20 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
87.253.232.0/21 REJECT 454 5.7.1 Mailgun mingles your mail with mail
from spammers. Change Email Sending Provider, or ask Mailgun to clean up.
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