prevent imap timeout while syncing large mailboxes?

[Peter P. <pet...@fa...>]

Hi, I am trying to sync a rather huge mailbox ~50k messages to a slave
that has a rather slow CPU (RaspberryPi). But I am getting frequent
timeout errors at the following point
 C: 0/1  B: 0/1  M: +0/0 *0/0 #0/0  S: +0/41711 *0/0 #0/0
 Socket error on imap.whatever ([XXXX:XXX::XX]:143): timeout.

I assume that it takes mbsync a while to calculate which messages to
sync and that the imap server closes the connection? Is there a
workaround for this problem?

Thank you so much!
Peter