I am trying to exchange e-mails with a person overseas. He can receive my e-mails, but I cannot receive his. Is it because T-bird is not my default e-mail? (It is the only program I use though). I have Mail on my Win. 10 system, but I do not use it. Is that my default e-mail? And, if I make T-bird my default e-mail, will I have any conflicting issues, crashes, problems, etc. with Mail? And do I need to turn Mail off? Any input will be greatly appreciated. Thank You.