guam - many errors in syslog

Hi,

after putting some load (i.e. migrating mailboxes) on a kolab server I
see many guam errors (>50000 per day) like this:

Feb 11 09:16:01 mail guam[17433]: 09:16:01.474 [error] gen_fsm
<0.20974.0> in state passthrough terminated with reason: bad argument in
call to erlang:bit_size([<<"=\r\n:normal;font-style:normal;text-deco
ration:none;text-align:left;vertical-ali=\r\ngn:top;max-w...">>]) in
eimap:joined/2 line 487
Feb 11 09:16:01 mail guam[17433]: 09:16:01.474 [error] CRASH REPORT
Process <0.20974.0> with 0 neighbours exited with reason: bad argument
in call to erlang:bit_size([<<"=\r\n:normal;font-style:normal;tex
t-decoration:none;text-align:left;vertical-ali=\r\ngn:top;max-w...">>])
in eimap:joined/2 line 487

Does anyone have an idea what's happening there? What is the cause and
the effect of this error and how can I fix it?

Thanks and best regards,
David

-- 
encrypt!
gpg --keyserver pgp.mit.edu --recv-keys 6A25B6A3
Schl.-Fingerabdruck = 15FF 16DC 494C EABD 6DF8  B388 4EB8 056C 6A25 B6A3