100% CPU, app "not responding"

version 2.9.29
Sierra 10.13.2

Application worked great for trial and first 2-3 weeks after licensing.
Now hangs almost every time I open the laptop.
Mail is left running and nothing is being closed and relaunched.

SpamSieve app is at 100% CPU in Activity Monitor.
Attempting to access the app, results in Activity Monitor displaying “not responding”
Mail background tasks all hung(deletion, fetching, etc) Mail interface responds, but background work never completes.

Only solution is to open Mail Preferences, uncheck the SpamSieve rule, quit Mail, kill SpamSieve, relaunch Mail.
Recheck the SpamSieve rule.
All spam mail since last working usage of Mail now dumps into Inbox and needs to be manually deleted.

Attached are:

  • The Apple generated stack crawl etc when app is Force Quit from the above state.

I also have a screen image representing the stalled state, Mail, Activity Monitor and Force Quit windows.
In this image you can see that SpamSieve has accumulated almost 8 minutes of CPU time all the while Mail hung in the “Checking for Mail” state. Not included, as it has names and such on the screen that I do not want in a public forum.

spamsievecrawl.txt (1.11 MB)

Please send the screenshot to me via e-mail and also include a fresh sample of SpamSieve taken with Activity Monitor during the hang.

Also, are you running any additional network software, e.g. a VPN or firewall?