I use lmtp with exim.

Sent from my T-Mobile 4G LTE Device

-------- Original message --------

From: himbeere@shinymail.de

Date: 2/21/18 11:59 AM (GMT-06:00)

To: dovecot@dovecot.org

Subject: exim dovecot sieve

Hello list.

I have just a generic question. Exim delivers fine to dovecot-lda. My
problems are the logfiles. Whenever I recieve a message
Exim writes to dovecot.log as the user who recieves the mail. This
forces me to have that logfile world writeable. I don't
really like that. How do you guys deal with that? Here my transport:

dovecot_delivery:
   driver = pipe

   # You may or may not want to add -d $local_part@$domain depending on
if you need a userdb lookup done.
   command = /usr/libexec/dovecot/dovecot-lda -f $sender_address

   message_prefix =
   message_suffix =
   log_output
   delivery_date_add
   envelope_to_add
   return_path_add
   #group = mail
   #mode = 0660
   temp_errors = 64 : 69 : 70: 71 : 72 : 73 : 74 : 75 : 78

thanks and best regards
t.