Why are emails from Amplemarket suddenly bouncing?
The Amplemarket help pages give 3 common reasons. The first to rule out: Microsoft can restrict a mailbox when emails sent from it are detected as spam, and its emails can then bounce.
Is it broken, or just quiet?
A number can fall because fewer people came, or because something stopped counting them. Below are the causes the Amplemarket help pages give, and how to check each one yourself.
What causes it?
Microsoft can restrict a mailbox when emails sent from it are detected as spam, and its emails can then bounce.
In the Amplemarket help:
Users may become restricted by Microsoft because the emails that they have sent were detected as spam
Microsoft Account Blocked:- "550 5.1.8 Access denied, bad outbound sender", read 2026-11-12.Sending a lot of email, or raising volume too quickly, can lead to a restriction, as Amplemarket's knowledge base explains.
In the Amplemarket help:
It could be an indication that you are sending too much volume or have ramped up your volume too suddenly in Amplemarket.
Microsoft Account Blocked:- "550 5.1.8 Access denied, bad outbound sender", read 2026-11-12.Newer mailboxes and domains can be more likely to meet this kind of restriction.
In the Amplemarket help:
It is normal for this kind of restriction to occur, especially for mailboxes or domains that are relatively young.
Microsoft Account Blocked:- "550 5.1.8 Access denied, bad outbound sender", read 2026-11-12.
How do I check it myself?
Look for the bounce message in Amplemarket and in your Microsoft inbox to confirm what is happening.
In the Amplemarket help:
You can check for this bounce message both in Amplemarket and from your Microsoft Inbox.
Microsoft Account Blocked:- "550 5.1.8 Access denied, bad outbound sender", read 2026-11-12.Check that warmup is on for your mailboxes and that sending stays within the recommended volume.
In the Amplemarket help:
Ensure that you have Email Warmup enabled for your mailboxes and are following the sending recommendations.
Microsoft Account Blocked:- "550 5.1.8 Access denied, bad outbound sender", read 2026-11-12.
How does Amplemarket work with Feder?
- Connect Amplemarket to Feder and it joins your Reach apps.
- When you connect Amplemarket, Feder checks the connection straight away and shows Connected only when that check passes. If a reading cannot be taken later, Feder shows it as not read, never as zero.
Some numbers are too quiet to judge daily, such as a form filled in a few times a week. Until there is enough of your own history to judge a change, Feder says it is still learning and scores nothing, rather than guessing.
See whether you can trust the numbers in Amplemarket, one of your Reach apps. Feder only reads. It never changes anything in Amplemarket.
What else goes wrong with these numbers?
- Why are fewer leads being contacted in my Amplemarket sequences?Amplemarket
- Why are so many of my Amplemarket leads showing as excluded or recently contacted?Amplemarket
- Why did Google Analytics stop collecting data?Google Analytics
- Why aren't my key events showing in Google Analytics?Google Analytics
- Why does Google Analytics show (not set)?Google Analytics
See every question.
Where do these answers come from?
Every cause and check on this page comes from the Amplemarket help pages, quoted above with the date we read them. Last reviewed 2026-11-12. We read them again by 2027-11-12. If one changes, this page changes or comes down.