SendMail & Domain Help ............pls!

[kevin]

I have this very curious problem with sending mail to my Linux machine.

I CAN send mail via the following rules to name at domain.com
	1. Sent outside my ISP network 
	2. Sent inside my network
	3. Sent first outside my ISP, then I can send within ISP.

My problem is when I send mail to name at domain.com
WITHIN my ISP, (Internet Service Provider) network.
It comes back mail returned saying it cannot find address.
My ISP hosts the domain name.

Now this problem only occours with my virtual domain.
My main domain, qualico.ca works perfectly and is not hosted by my ISP.
Named files are setup the same for both virtual and main.

I have a feeling this is a DNS problem.
I have read the cf/Readme and batbook.
I have checked the FAQs.
I have checked the newsgroups for similar problems.
I have tried various settings in sendmail.cf.
I have researched and read about Masquerading and Virtual Hosting.


If anyone can help me with this problem, I would be very grateful.
If you want my mail logs, sendmail $w and -bt info, or want returned mail
please contact me at kevin at qualico.ca.
I'll post the info you need.

Any suggestions or thoughts are always welcome!
At this point I'll stand on my head if you think it could help.

-Kevin
kevin at qualico.ca