Well we were doing well without a crash for several days but this morning mail quit again for no apparent reason. I have an Etrecheck report that I will post below in advance. Safe mode - hard to tell if effective because sometimes it takes days to crash! Here is what I have tried so far, sequentially. Terminating with uncaught exception of type NSException *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -: index 9223372036854775807 beyond bounds '
![mail app for mac sierra not sending emails mail app for mac sierra not sending emails](https://www.rawinfopages.com/mac/sites/default/files/sites/default/files/img17/mail-search.jpg)
The crashlog shows the following similar crash. Sometimes several times daily and sometimes not for a few days.
![mail app for mac sierra not sending emails mail app for mac sierra not sending emails](https://support.hostpoint.ch/images/EN/produkte/email/applemail_sierra_4.png)
I am at my wit's end with this and so any assistance would be greatly appreciated.