[Mailman-Users] Microsoft blocking our Mailman lists

Jayson Smith jaybird at bluegrasspals.com
Sun Oct 7 13:00:58 EDT 2018


Unfortunately, yes, I have seen this behavior from Microsoft. I have no 
idea what triggers it, but my Linode IP has been blocklisted twice, once 
a bit over three years ago, and another time less than two weeks ago.

If you haven't already, try signing up for their Smart Network Data 
Service at https://postmaster.live.com/snds. On the FAQ page there you 
will find a link to submit a delivery support ticket, you can request 
your IP be removed from the blocklist. I have no idea how long your IP 
will stay on their blocklist if you don't request removal. Before 
requesting removal you should probably use some online checkers to 
insure you're not on any other blacklists, check your IP at 
senderscore.org, etc.

The last incident inspired me to move a high-traffic list I run from 
Mailman to Groups.IO.

Hope this helps,


On 10/7/2018 12:28 PM, Lindsay Haisley wrote:
> FMP's mail and web server is a virtual server at Linode. We run half a
> dozen Mailman lists or so, all opt-in lists for a couple of non-profits
> and small business customers, all of which have been running
> successfully for many months. Today I got a large number of
> unsubscription notices from one of our lists, all of them for addresses
> at hotmail.com, msn.com and outlook.com. They contain the following
> text:
>   hotmail-com.olc.protection.outlook.com []:
>   >>> MAIL FROM:<aftm-bounces+clarkson-66=hotmail.com at lists.fmp.com>
>   <<< 550 5.7.1 Unfortunately, messages from [] weren't
> sent. Please contact your Internet service provider since part of their
> network is on our block list (S3140). You can also refer your provider
> to http://mail.live.com/mail/troubleshooting.aspx#errors.
> [SN1NAM04FT034.eop-NAM04.prod.protection.outlook.com]
> Has anyone seen similar problems recently with Microsoft mail customers
> who are Mailman list subscribers?

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