My main employer (CipherSpace) runs a mail system with a few dozen SMB customer 
domains and a long low-volume history of good behavior. ~2 weeks ago we had an 
end-user password cracked an a very sneaky spammer managed to get through a 
couple thousand spams over the space of about a day, at a slow and steady pace 
via webmail. It got our outbound IP throttled briefly at Yahoo/Oath, cleared up 
in short order. I mention this because it is our only incident in many months 
(years?) and has been followed (maybe coincidentally) by our first collision 
with the infamous Microsoft S3150 block since we switched to funneling all of 
our outbound to a single IP a couple of years ago. That merge was a response to 
chronic flickering S3150 problems without any discernible cause hitting 
single-client outbounds seemingly at random. It seems like bundling the volume 
helped maintain a good-enough reputation on the merged outbound 
(74.115.114.191) for the problems to subside, until this weekend.

We have JMRP and SNDS set up. We've never received a single report. No 
addresses have issues according to SNDS. JMRP has never sent us a single 
report, as far as I can tell.

I have done the dance at https://sender.office.com to get delisted, trying 3 
different email addresses before finally discovering that the email 
confirmation messages it sends are so broken that SpamAssassin *AND* 
Outlook.com's filters think they are junk in ridiculously bad ways. The issue 
has supposedly been escalated to Microsoft Support thrice, after I worked 
around the fact that MS thinks their own administrative mail is junk...

Meanwhile, my boss tried working another route and has opened 2 tickets: 
SRX1544040988ID asking for just the one IP and SRX1544076120ID for the whole 
/24. Got the dreaded "Not qualified for mitigation" boilerplate response to 
both.

What is the way out of this? It feels a lot like intentional anticompetitive 
behavior, but I'm paranoid.


-- 
Bill Cole
[email protected] or [email protected]
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire

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