Hi Heiko,
> Is there any delay between STARTTLS and 454?
No the result is immediate.
> Could it be that you miss enough entropy? (Check
> /proc/kernel/random/entropy_available during the failing connection).
I just did 'cat /proc/sys/kernel/random/entropy_avail' and got '0' as a
result. Does it look bad?
> And, I'd guess, there *should* be some hint in the logs.
Maybe we are looking at the wrong log file. Which one would you look at,
'/var/log/exim4/mainlog'?