My outgoing mail is being blocked with error 554 5.7.520 AS(4810) even with normal JPG attachments.”

Question

My outgoing mail is being blocked with error 554 5.7.520 AS(4810) even with normal JPG attachments.”

Do I need to request that the reputation flag on my account be cleared?

Answer 1

I found out that it was the file type I was trying to send. For some reason, a webp file was being flagged as spam. That was the problem. I converted the webp file to a JPG file, and it sent without a problem.

Answer 2

Hello Michael Nelson,

That error alone doesn’t confirm there’s a reputation flag on your account that you can request to clear. Could you try sending a short, plain-text message with no attachment or links to two different recipients? Please let us know whether both fail, and share the full delivery-failure message with any personal details removed.

That will help narrow down whether the rejection depends on the message or affects your outgoing mail more broadly.

Answer 3

The 554 5.7.520 AS(4810) error generally indicates that the message was rejected by Microsoft's outbound spam/abuse protection. The fact that the attachment is a normal JPG does not necessarily mean the attachment itself is the cause.

I would recommend checking the following:

Try sending the same message without the attachment. If it succeeds, compare the message/attachment characteristics.

Try a different JPG with a smaller file size and a simple filename.

Check whether the issue occurs when sending to multiple recipients or only to a particular address/domain.

Review your Outlook.com account for any recent unusual sign-in or sending activity and make sure the account is secure.

Avoid repeatedly retrying the same blocked message, as repeated attempts may not resolve a reputation-based restriction.

If the issue continues even with ordinary messages and no attachment, this is more likely to require Microsoft's automated account/reputation systems to be reviewed rather than being caused by the JPG itself.

For Outlook.com accounts, the appropriate next step is to use Microsoft's official Outlook.com support channel so the account-specific sending restriction can be investigated. There isn't a user-side setting that can simply clear an outbound reputation flag.