Spamsieve using Mail extension with Sonoma 14.7 causing Mail to hang

Why is that? Does Mail unfreeze before you can open Activity Monitor?

The setting for the number of seconds affects both Filter spam messages in other mailboxes and Check inboxes for new messages not sent to Mail extension.

Yes.

It’s possible. You can see in the Settings window next to the Check Now button which mailbox SpamSieve is filtering at any given time. So that can tell you whether SpamSieve is doing something during the hang and which mailbox it might be related to.

Yes, there is a bug in Mail where sometimes it throws away message data that’s already been downloaded, and if SpamSieve later asks for that data it can get bogged down refetching it if it’s also doing other stuff.

The page recommends instead that you increase the time interval.