WARNING:
These Instructions are NOT the OFFICIAL
instructions to install Sendmail-8.8.5 on your machine but simply notes that I compiled when I installed Sendmail-8.8.5 on my machine. 

USE THESE NOTES 
AT YOUR OWN RISK!!

Sendmail-8.8.5 Installation Instructions  
for installing Sendmail-8.8.5 on a stand alone machine. I assume that you have PPP running already and that you can web browse etc...

This installation will permits you to forward email to your ISP's mail server. Local mail will be delivered as usual and any mail that is external to your machine will be exported to your ISP's mail server. 

The main advantage of this configuration is that all your email will be queued. So you can type and send email without actually being online. Onces online you simply use the EmptyQ application to empty the mail that is in the queue to be forwarded to your ISP's mailserver. In using older versions of sendmail, your mail cannot be queued and bounces right back since your not online.

Login as ROOT

Install the packages:

m4.1.4.NIHS_bsd
Just install it, nothing further is needed to do with this package.

sendmail-8.8_5

EmptyQ.app
Install EmptyQ.app in /LocalApps

You need the following information:
mailhost adress
Your host name

Follow the following instructions:

In Sendmail-8.8.5-config_OpenStep directory open and edit the file called mydomain.m4 

Original:
define(`LUSER_RELAY',relay:nebula.cam.org)dnl

Yours:
define(`SMART_HOST',relay:your..host.name.domain)dnl

Now save the file.

In Sendmail-8.8.5-config_OpenStep directory open and edit the file called userdb 

In this file you need to put all the users on your machine that will send or recieve mail you can add as many as you need:

Original:
root:mailname 		myname@domain.com
myname:mailname 	myname@domain.com
me:mailname 			myname@domain.com

Yours:
root:mailname 		yourname@domain.com
yourname:mailname 	yourname@domain.com
otherpeople:mailname 	otherpeople@domain.com
me:mailname 			yourname@domain.com

Now take all the files in Sendmail-8.8.5-config_OpenStep directory and copy them to /etc/sendmail

The following files (possibly more) should at least be in your /etc/sendmail directory:
README.rtfd    
mydomain.m4     
sendmail.cw
inst_sendmail*  
next.mc         
userdb

Now there's ONLY one thing left to do. Open a terminal shell and execute the inst_sendmail script. This script will finish the sendmail configuration. Onces this is done. Your sendmail should be installed and working correctly!

Execute this script:

/etc/sendmail/inst_sendmail

I hope this has helped you install and configure your email system! I have done this several times and it works!!! So it should also work for you. Good luck.