As usual the default logcheck rules are not sufficient. These are the rules I added to my ignore.d.server/dovecot file:
^\w{3} [ :[:digit:]]{11} [.[:alnum:]-]+ dovecot: lmtp([[:digit:]]{5}): (Connect from local|Disconnect from local: Successful quit) ^\w{3} [ :[:digit:]]{11} [.[:alnum:]-]+ (dovecot: )?(deliver|lmtp)([-.@[:alnum:]]+): sieve: msgid=>?( (((added by )?[^[:space:]]+|sfid-[[:xdigit:]]+))?)?[[:space:]]: (stored mail into mailbox '.'|marked message to be dis carded if not explicitly delivered (discard action)|(forwarded to|sent vacation response to|discarding vacation response for message implicitly delivered to|not sending vacation response to system address|discarding vacation respon se to mailinglist recipient|discarded vacation reply to|discarding vacation response to (auto-submitted|precedence=(bulk|Bulk|list)) message from|discarded duplicate (vacation response|forward) to) <[^[:space:]]>)$ |