i have a LAMP server im using to test my websites with and im behind a router so the web server is not accessible to the outside.

i want to use sendmail as my mailserver while testing my php applications and also because that is what my hosting provider uses. my test webserver is not accessible to the outside and im running behind a broadband router. all i really need to do is setup about 5 or 6 different email accounts for recieving email from the web site after orders are completed etc also maybe another 5 or 6 email accounts for vendor emails (suppliers).

-wait a min, i think i just answered my own question -
maybe i dont need to even send to external addresses, i could just create users on my linux box for use with testing my web site. when i registered a new user, what would i specify for their email address,
user_name@localhost.localdomain -or- user_name@my_internal_domain.com ?

that brings me to my next question. i dont really want to run DNS just for internal networking, id rather just keep my machines as dhcp clients. id like to be able to access my web server via a name like www.testserver.com and have it resolved to an internal IP, do i do that in the hosts file and how will that affect the sendmail config settings ?


extra -
At present ive been modifying the sendmail.mc file and ive noticed sendmail takes a long time to both startup and send an external mail as well, such as to my yahoo account. ive started out by setting a smart_host to my isp and the masqaraude_as as my isp domain. i setup a dummy internal domain as well in the /etc/hosts file. and this domain is listed in the maillog as causing problems such as
Apr 6 15:11:25 billybob sendmail[7150]: starting daemon (8.12.10): SMTP+queueing@01:00:00
Apr 6 15:11:25 billybob sm-msp-queue[7157]: My unqualified host name (billybob) unknown; sleeping for retry
Apr 6 15:12:25 billybob sm-msp-queue[7157]: unable to qualify my own domain name (billybob) -- using short name
Apr 6 15:12:25 billybob sm-msp-queue[7160]: starting daemon (8.12.10): queueing@01:00:00