[Exim] Frozen messages in queue...

Hello, it's me again :)

I'm now with 4 domains and circa 1000 users running in exim, very fast
:)

the thing is, there's a bunch of frozen messages waiting for the retry
time, but a lot of them are bounces and such. My question is, for
example, looking at the msglog for a this frozen message:


2003-01-21 01:33:37 SMTP error from remote mailer after RCPT
TO:<opitmouinf2@???>: host mx3.hotmail.com [65.54.254.140]: 550
Requested action not taken: mailbox unavailable
2003-01-21 01:33:37 opitmouinf2@??? R=dnslookup T=remote_smtp:
SMTP error from remote mailer after RCPT TO:<opitmouinf2@???>:
host mx3.hotmail.com [65.54.254.140]: 550 Requested action not taken:
mailbox unavailable
*** Frozen (delivery error message)

Messages that get errors like that (550) should be freezed and scheduled
for a retry? there's 65K messages in the queue, and I'm starting to get
worried... some of them are from amavis getting a 75 error signal (just
3 or 4), but the others are timeouts and 550 errors...
It's normal or my setup is freezing erroneously?

[]s
core