Hi George!
The company that I work for uses Lotus Notes 4.62. One of the biggest reason for them to have chosen Notes was for its well known security. This also makes it a problem specialy when you have to carry user id files around if you plan to log in to different workstations.
As far as integrating Emailing capabilities in your VFP apps, I use IDSMail with some complaints. For example:
When sending Email, IDSMail does NOT yet take advantange of the password synchronization that Notes has with NT. In other words, whenever I want to email, I need to check for who the current user is and "hardcode" the password for that user. Just the word "hardcode" makes me shiver!
We also use SQLPump which allows you to write a Notes agent that can import a VFP table into a Notes Database.
Regarding reliability, Lotus Notes is very reliable. Developing in it is another monster.
If you need additional help, please feel free to contact me.