I think lesser known TLDs are the problem. I have had a .net domain and used the email address (and its self hosted these days, which has been a problem with sending to hotmail) and have never had it rejected or confuse anyone.

ON the other hand I had a website with a ccTLD and one guy kept trying to add .com to it - his own country's ccTLD!

i love my .town email, and ive had very few rejections from websites. maybe like 2 ever. plus i can make up departments for each site i signup for