Over Outlook 365, ja dat gebruiken wij.
Het probleem treedt alleen op bij het verzenden naar een Ziggo-account (en Casema). Andere adressen werken normaal.
OP de mail kregen we dit bericht terug:
This message was created automatically by mail delivery software.
A message that you sent has not yet been delivered to one or more of its recipients after more than 72 hours on the queue on server20202.hostingking.com.
The message identifier is: 1m4h6o-00BsCT-UG
The subject of the message is: test 17-07-2021
The date of the message is: Sat, 17 Jul 2021 11:59:46 +0200
The address to which the message has not yet been delivered is:
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host mx.tb.mail.iss.as9143.net [212.54.42.8]
Delay reason: SMTP error from remote mail server after initial connection:
421 mx11.tb.mail.iss.as9143.net mx11.tb.mail.iss.as9143.net MXIN108 Failure to determine Reverse DNS for your IP 193.176.184.202. Fix or retry later. ;id=5uIfmfMkhGWZz;sid=5uIfmfMkhGWZz;mta=mx11.tb;d=20210720;t=201704[CET];ipsrc=193.176.184.202;