Microsoft S3140: sending IP reputation block
Microsoft / Outlookreputation_blockaction: pause
S3140 is Microsoft's internal reason code attached to a block, and it points at the reputation of the sending IP. You will normally see it alongside a 550 5.7.x response. Treat it the same as any Outlook reputation block: stop sending from that IP and work the delisting.
What it looks like in the log
550 5.7.1 Unfortunately, messages from [x.x.x.x] weren't sent. Please contact your Internet service provider. You can tell them that Outlook refused to accept your message. [S3140]Why it happens
- Poor IP reputation at Outlook, usually complaint-driven.
- Little or no sending history from this IP to Microsoft domains.
- Volume out of proportion to the IP's established reputation.
What to do
- Enrol the IPs in SNDS so you can see the complaint and trap data behind the block.
- Join JMRP so Outlook complaints reach your suppression pipeline.
- Request delisting once, with the cause already fixed.
- Warm the IP back up slowly rather than resuming at previous volume.