mail() cannot find an email server to send the email.
Also this means that it is now running on a windows machine:
Warning: Server Error in c:\inetpub\wwwroot\alumni\mail.php on line 22
Your test server is probably a Unix/Linux machine.
The mail() function uses sendmail on unix machines to send email but windows machines don't have sendmail.
In the php.ini file (this can be found at c:\winnt\php.ini) there is the following:
[mail function]
SMTP = localhost ;for win32 only
sendmail_from = me@localhost.com ;for win32 only
;sendmail_path = ;for unix only, may supply arguments as well (default is 'sendmail -t -i')
This has to be setup correctly for the mail() function to work and has to point to a SMTP server that will send your email.
Windows servers by default do not have any POP (incoming mail) or SMTP (outgoing mail) services running. This is because they want people to buy Microsoft Exchange for lots of cash.
There is however an SMTP service that can be installed in Internet Services Manager to send or relay email to a mail server (but not receive)
The SMTP Service is probably not installed and configured in the Internet Services Manager on that machine.
If your network admin has no clue then she should try basket weaving as a vocation 😉
This is an Admin issue and requires Administrative access to the server in order to configure it.