creat a user with proper format , it's ok .

but export these user ,and import to another database,

these user can't create a custom ,

it also waring

"Unable to send email, please configure the sender's email address or alias."

I had the same problem and I found that the Partner that was related with my User account had no email address. After providing an email address, everything worked fine.

It's been a while since when the o.p. asked but I had the same problem and landed here after a google search. I found what was the problem in my case so...

Hi Mihir,

Maybe the system is trying to send an email to newly created user but it is not able to send maybe because user Administrator's email address(login) is not in proper format. Maybe Admin user login name is just admin, try to change it to any other email address maybe your private or anonymous(nouser@nonedomain.com). Hope then it will work.