1400: 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. ...