[exim] mails with many recipients

Hi,

one of our client mailservers lately has to deliver mails with a lot of
recipients (>400 each mail). BTW: I made sure it is not spam :-) .

I added

remote_max_parallel = 50
queue_run_max = 10

to the configure script but see a strange behaviour. Once the big
message is delivered to exim it sticks in the queue for quite some time
(several minutes) without any big action (maybe one or two delivery
attempts). Then suddenly hell breaks loose and exim is delivering with
many parallel processes (all with -Mc messageid). I suspect that exim
for some reason is not trying to deliver the mail at once and instead is
delivering those mails during the next queue run (15 minutes here).

If so: Is this the default/desired behaviour? Can I configure this? Exim
version in question is 4.41 btw.

Thanks a lot!


Regards,
JP