Look in the junk folder. It happened once with me. I was clueless then I found them in my junk folder. I was using gmail client.
Indeed.
That's somewhat weird. I usually just received them in my standard inbox.
Seems like some shitty algorithm started to move them into the junk folder automatically.
And in addition to that, the junk folder did not synchronize itself (accessing this mail account via mobile online).
All sorted out, thank you!