This doesn't happen very often but it's annoying & frustrating. Last night just before going to bed I received an e-mail from someone asking for help with CFS1. I replied in the usual way by clicking the "Reply" option. My mail is being returned as the address is not recognised. Can someone please explain to me how this can possibly happen when I sent it to the same address that the e-mail came from.

Puzzled from Worthing.