I believe Francis led you down the right road.  In the sendmail.mc file

dnl # Uncomment and edit the following line if your outgoing mail needs to
dnl # be sent out through an external mail server:
dnl #
dnl define(`SMART_HOST', `smtp.your.provider') dnl


smtp.your.provider is the server that will actually send your mail.  This 
should already be in your sendmail.mc file unless someone removed it.  You will 
have to remove dnl from the beginning and end of the line. and edit 
smtp.your.provider to your actual server that sends the email

In our domain sending email out the normal port is restricted (denied by 
firewall and vlan settings) on campus except for the campus mail server which I 
define in my sendmail.mc file as the smart_host.

After editing the file you will need to run

make -C /etc/mail

which updates the sendmail.cf file.  Then restart sendmail.

Thomas


On Friday 26 March 2010 15:08:17 you wrote:
> Hi all,
> 
> I sent this to web4lib, but maybe someone on this list would have a
>  solution?
> 
> I don't know if anyone on this list can give me a hand, but I'm trying to
>  configure sendmail on our library's LAMP server. I have to use a different
>  IP address specifically used for outgoing email instead of the box's IP.
>  Does anyone know where/how I can configure this?
> 
> thanks,
> 
> Junior Tidal
> Web Services and Multimedia Librarian
> New York City College of Technology, CUNY
> 300 Jay Street
> Brooklyn, NY 11210
> 718.260.5481
> 

-- 
==========================================
Thomas McMillan Grant Bennett           Appalachian State University
Operations & Systems Analyst            P O Box 32026
University Library                                Boone, North Carolina 28608
(828) 262 6587

Library Systems Help Desk: https://www.library.appstate.edu/help/
==========================================