Mail forwarding broken to @ru.nl

Due to a change in how the Microsoft Exchange server validates e-mail, mails sent to an @science.ru.nl address (or similar domains for which we accept e-mail) from an external domain and with a forward to your @ru.nl mail are very likely to be dropped, because the receiving server at Microsoft considers this mail forged, in the sense that the sending client did not address the same domain as the receiving domain. This also applies to our Mail Aliases with @ru.nl addresses in them, when they are addressed from an external mail domain. The forwarded e-mail will be silently dropped, so senders will not notice a problem.

Mitigations:

• (Only if you have external people use your @science.ru.nl address); disable forwarding in your diy or add CC option to receive a copy in your science mailbox (you can access that via roundcube or mail client).
• Or stop using your @science.ru.nl address in e-mail communications.

Not affected: users who have no forward and mailman-lists @science.ru.nl will also keep working.

We have notified the central mail administrators about this issue.

Update; our mailsenders have been added to the trusted list.