We have been having issues with many of our emails showing the error below and not being sent. The addresses are good so not sure why this is now happening. The CMS mail settings are set up as SMTP, non-secure for now. Port 26. Appreciate any assistance.
Subject: Mail delivery failed: returning message to sender
This message was created automatically by mail delivery software.
A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:
(ultimately generated from firstname.lastname@example.org)
"Domain website.com has an outgoing mail hold. Message will be reattempted later":
retry timeout exceeded
AcyMailing Triggered at 12 March 2020 03:00
0 messages processed : 0 successful, 0 failed