Syncing emails from external server like Gmail

[Vitalii]

Greeting

I've managed to backup my emails from external email server via dsync
and imapc: protocol like this:

doveadm -Dv -o imapc_user='user at gmail.com' -o imapc_password="pass"
-o imapc_host=imap.gmail.com backup -R -u duke at ejoom.com imapc:

taken from https://wiki.dovecot.org/Migration/Dsync

I wish to do regular syncing of 5min interval to substitute 'getmail'
program.

When I repeat the command It doesn't download all the attachments(!good)
but It seems that at retrieve all the the GUIDs and UIDs(!bad) again
that take quite long considering 30K emails. 
The question is how to speed it up and retrieve only new emails? Does
anyone have a solution for regular synchronization? What is the best
way?


Logs look like this: 
  https://gist.githubusercontent.com/vnagara/87e0da1b21b51f68fd74270b3ec653b3/raw/70ebd6d98338aa80c33ecabf7f108f5e7ce10d49/dsync%2520logs.log

It wrights that "Mailboxes are equal" but still verifies all the UIDs
again.


Thanks.
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