Apple Mail hangs after installing SpamSieve 3.1.3

I’m on a mac running macOS 15.5 and Apple Mail. I just updated to SpamSieve 3.1.3 and now Apple Mail shows downloading 1 of 1 but otherwise is not responding. What do I do?

No other reports of that so far. Please record a sample from the Mail app so we can see why it isn’t responding.

What does “record a sample” mean since Apple Mail isn’t responding? BTW I use gMail as the source for my mail and I’m writing this from mail.google.com.

Problem resolved after force-quitting Apple Mail.

Using the Activity Monitor app, as described here.

Thanks. I never knew that you coukd do that.