This has been discussed before, but I cannot find a thread that would get to the bottom of this: how to setup ZCS so that the out of office subjects would display all right on most receiving clients?

Right now, the subjects to my out of office replies look like this:
=?ANSI_X3.4-1968?Q?Re:_Muistutustoiminto_nyt_k=3Fyt=3Fss=3F?=

The receiving client is a recent version of Thunderbird. The subject is in finnish and contains some -characters. Normal messages with these characters are fine.