Indexer opening emails in write mode ?

Hi,

I have dovecot indexer working inside AppArmor, and I am confused by some error messages:

name="/home/users/andre/mails/maildir/.Sent/cur/1682251668.M110083P109814.pigment,S=1743,W=1776:2,S" pid=111784 comm="indexer-worker" requested_mask="wd" denied_mask="wd" fsuid=1001 ouid=1001

Why the indexer would open email files in write mode, please ?

Thanks for your advice