Send Failed Exception

[Ramachandran Sridhar]

If anyone has a clue on this one please let me know as I am stuck with this stuff last couple of days..
I receive an error message when trying to send a mail through my Java mail client as follows:
javax.mail.SendFailedException: Invalid Addresses;
nested exception is:
javax.mail.SendFailedException: 550 Relaying is prohibited
at java.lang.Throwable.<init>(Compiled Code)
at java.lang.Exception.<init>(Compiled Code)
at javax.mail.MessagingException.<init>(MessagingException.java:52)
at javax.mail.SendFailedException.<init>(SendFailedException.java:73)
at com.sun.mail.smtp.SMTPTransport.rcptTo(Compiled Code)
at com.sun.mail.smtp.SMTPTransport.sendMessage(Compiled Code)
at moeza.mail.BIMInternetSendThread.run(BIMInternetSendThread.java:84)

The mail server above is iintec.com. When I change to another mail server (e.g. indiainfo.com) I get a somewhat different message as follows:

javax.mail.SendFailedException: 473 [e-mail] you should authenticate first
at java.lang.Throwable.<init>(Compiled Code)
at java.lang.Exception.<init>(Compiled Code)
at javax.mail.MessagingException.<init>(MessagingException.java:39)
at javax.mail.SendFailedException.<init>(SendFailedException.java:42)
at com.sun.mail.smtp.SMTPTransport.rcptTo(Compiled Code)
at com.sun.mail.smtp.SMTPTransport.sendMessage(Compiled Code)
at moeza.mail.BIMInternetSendThread.run(BIMInternetSendThread.java:91)

I am not quite clear what authentication is required for hotmail email ID.. It is curious that all mails pertaining to the mail server domain gets sent without a hitch but any mail that is outside of the domain gets bounced..
If anyone has faced similar difficulties please let me know the solution..
I thank you all in advance..