Undeliverable in Outlook XP SP3

[snail112]

I get the following message when trying to send e-mail

The following recipient(s) could not be reached:

'[email protected]' on 2007/05/02 23:27
554 5.7.1 <unknown[My router/modem IP]>: Client host rejected: IS ADSL

This started after getting my 3 e-mail addresses from X-DSL and loading them to the Email Accounts.

The router/modem is a Mega 100WR2.

If it is the Mega 100WR2 it is going to have a close encounter with a 9mm FMJ.

Please help