since our recent upgrade to NE 4.5.4 we have problems with the german umlauts. They are not shown both in the Web frontend and in Outlook.
Instead you see something like :
Bitte prüfen Sie möglichst umgehend ... and ... Beste Grüße.

We had nor such problems before the upgrade. Strangely this does not occur in all mails. It seems only some of text-only mails are affected.

Another strange thing is: in my out of office reply (where I only change dates) suddenly all the umlauts where changed like quopted above.

Any idea what the problem might be?