Gregory's Server100%
They silently delete mail to/from Tuta!
I have checked and double checked (although not for a little while) and it just disappears, it doesn't even make it to the junk folder!
If I was an independent, I would be organising a class action against email for industrial sabotage.
@Tutanota
I have just checked it again with my own personal accounts and it worked this time. Perhaps thaey have realised they were not going to get away with it.
I will do another test with a friend where the emails are different.
p.s. there was also a recent change where gmail was refusing anything without an SPF record. I had to go through and update a lot of domains/mail account settings manually so they would work again.