On Sat, 17 Nov 2018, Vasili Wylie wrote:

> it is not all about office365, I don't use that and I was kicked off.

somewhat humorously, I too was kicked off over the weekend.  
The accompanying message made it look as through the 'too many 
delayed or bounced pieces' trigger was hit, with a 'look-back 
of three months

That is a configurable setting in Mailman, and may have 
inadvertently been encountered when rolling in a backup and 
not expressly disabling that counter for a few days to let it 
expire old pending non-sends

-- Russ herrold