Emails being auto added to the "Bin" folder - Why?

I often (daily) can not find an email by searching my mail boxes. If that’s the case I then have to head over to the “bin” folder and I will often find it there. I then have to move it out of the bin.

There seems to be no rhyme or reason at all for this. There are no patterns, keys, tags or markers I’m doing that is putting them in the bin. It seems to be completely random so I can’t give a full breakdown bug report.