problem with mail.com on a public computer

I recently set up an email account with mail.com, using a computer in
a public library.

I then tested it by sending an email to it from my own yahoo address,
but this was returned undelivered. I then logged off the mail.com
account and immediately tried to log on again, but it wouldn't take my
password!

Any idea what's going wrong here? I've tried contacting mail.com but
they're not replying.

Thanks in advance.