I just switched my emails back to Apple Mail v10.1 (3251) in the past week and have installed SpamSieve v2.9.26. I had been using the Sierra betas but just installed the released Sierra 10.12.1 version yesterday. These occasional crashes have been happening on both the betas and this morning with the released version. I also do not know if Mail is crashing by itself or if the combination of SpamSieve and Mail is causing the crashes. I suspect the latter since Mail seems to crash when I am trying to train SS that a new email is either spam or good.
I’m not sure what diagnostic information you want so I have attached the SpamSieve Log, SpamSieve Statistics and the User Crash Report generated and sent to Apple. Let me know if you need more information or how I can help solve the crashing.
I just went back to Mail to continue training and every time I click on the email I was training during the first crash, Mail crashes again. I’m going to have to delete that message before I can go forward. I have the newest crash report but I cannot attach another file. Let me know if you need it.