Email sending not working using Apache James
Solution 1:
I think problem caused by this:
Email servers before accepting any mail do a reverse dns query. They check the ip for domain that the email came from and the ip that email is really came from.
If ip of domain and ip of email sender does not match, mail servers think that email is junk or spam.
Here since your domain (localhost) is not a valid address when Email server send a reverse dns query does not get an IP and think your mail is junk or spam.
For more information check this: http://wiki.junkemailfilter.com/index.php/Fixing_Reverse_DNS