What is going on when Mail.app says 'changing flags' on IMAP accounts (just curious)

[masonmark]

Hello, SpamSieve rocks, thank you. I recently reset my corpus since the tips suggested it was too bug and it had been over a year.

As I select a few dozen known good messagesand choose 'Train as Good', I notice that the Mail.app activity monitor window briefly runs through dozens of operations that read "Changing flags" and indicate that some network operation is happening.

What kind of flags are being changed here? (I am just curious to know, it was not a problem.)

Thanks,
--
Mason

[Michael Tsai]

What kind of flags are being changed here?

The flag that the message is junk and (possibly) the unread flag and color.