How to temporarily disable SpamSieve from Apple Mail

Several months ago I came here and made a forum account so I could ask what role, if any, SpamSieve might have been playing in causing Apple Mail to be taking upwards of 15 seconds to open. In the midst of some back and forth posts those months ago, Apple Mail suddenly (and I still don’t know why) began opening in 2 seconds again as if it magically fixed itself. But now, it’s happening again, even worse this time as it’s taking upwards of 25 seconds for Apple Mail to actually open after having clicked its icon in the Mac Dock. What is the simplest way of disconnecting SpamSieve from the process of opening along with Apple Mail so I can see if SpamSieves has anything at all to do with what is not working correctly. I am running macOS Catalina 10.15.4 and SpamSieve version 2.9.39. thanks

There is a bug in Mail/macOS 10.14 and 10.15 that can cause Mail to be slow to launch if a plug-in installed. This happens irrespective of which plug-in it is or what the plug-in does, because the delay occurs before Mail has actually loaded the plug-in.

The workaround, as described in the FAQ, is to go the General tab of Mail’s Preferences and click on Manage Plug-ins…. Uncheck SpamSieve.mailbundle and restart Mail. Then go back to Manage Plug-ins… and check SpamSieve.mailbundle. Now restart Mail again. In other words, you disable and then re-enable the plug-in.

Wow… Thanks Michael… I did ONLY what you said above about first unchecking and then after another restart of Mail rechecking the only plug-in I have coupled to Mail, the SpamSieve plugin. And doing only that, I went from 25 seconds or so to load Mail before doing those steps to pretty much instantaneous (1 second tops from clicking Mail in the Dock until the Mail window opens) after doing the steps you outlined… Do you believe Apple is aware of whatever is causing this bug??? Should we consider sending feedback to Apple or no???

thanks again… That put me back in a better place with launching Apple Mail. I will remember this bug going forward…

I reported the bug to Apple but have not heard back from them. I recommend sending them feedback so they know to prioritize this. Specifically, the issue is that Mail hangs in the FSEventStreamFlushSync function.