send mail is not working

for ex : i ahve aliases :

testuser

sendmail -v testuser@localhost < t.mail , this is working 

but when i am trying from anot开发者_StackOverflow社区her host

sendmail -v testuser@host.company.com < t.mail .. its not working .. i am not receiveing mail

what is the issue how to reslove it

Do you accept mail for host.company.com? Do you have a MX record for host.company.com pointing to your MTA?