Author Topic: Occassional email bouncing  (Read 225 times)

Tim Hall

  • Victoria is my queen
Occassional email bouncing
« on: 30 April, 2021, 01:40:13 pm »
I've been missing out on some emails from a contact.  One bounced this morning but was sent fine again a few minutes later.

Here's the bounce message:
host []
SMTP error from remote mail server after RCPT TO:<>:
550 5.4.1 Recipient address rejected: Access denied. AS(201806281) []

What's going on?
There are two ways you can get exercise out of a bicycle: you can
"overhaul" it, or you can ride it.  (Jerome K Jerome)


  • Timelord
Re: Occassional email bouncing
« Reply #1 on: 30 April, 2021, 02:54:55 pm »
Exchange is b0rked.
Careful, Kim. Your sarcasm's showing...

Re: Occassional email bouncing
« Reply #2 on: 06 May, 2021, 03:08:00 pm »

The message is getting to Exchange Online, but it is being rejected.  550 is generally a “mailbox not found,” but the status code is … interesting, as we know the mailbox exists and can successfully conduct internal transactions.

In this case, the temporary solution was disabling Directory-Based Edge Blocking (DBEB) by changing the customer domains (not the ones) in Exchange Online to InternalRelay.

Glad my job doesn't involve exchange.
A Few Apples Short of a Strudel