I have a very strange fault on my iPhone that I have been experiencing for at least a couple of years. It's pretty simple - when I reply to an email it sometimes sends the reply back to me instead of to the person who I am trying to reply to. It seems quite random, although I think it is only occurring within email threads with a bit of back and forth. 

It is driving me nuts as I reply to someone, assume they've received my reply, then later I notice my reply in my own inbox, then have to copy and paste it and resend it.

Is anyone else experiencing this, and is there any known solution?