For anyone with Lotus Foundations Start with the Domino add-on here is some undocumented information for you !
If you have a requirement for users Internet email addresses to be different from the Lotus Foundation Start account name, you can change the person document to reflect the new Internet Email Address (but don’t change the domain or the short name).
If you change the Domino short name and it does not match the LFS account name, the next time Domino is restarted the account will be removed from the Domino Directory. I know this from bitter experience.
Lets take a user called John Smith. He wants his Internet email address to be email@example.com
Foundations Account Name : jsmith
Domino Person document short name : jsmith (this is essential for synch purposes)
Domino Person Document Internet address : firstname.lastname@example.org
Remember that the acme.com specified in the Internet address must match your Domain Domain name on the Foundations server (the domain cannot be changed after installing Domino)
You may also want to look at setting the Configuration Document to use the Person Document Internet address for outgoing mail. Edit the server Configuration Document – MIME Tab – Conversion Options Tab – Outbound – Set “Lookup Internet address for all Notes addresses when Internet address is not defined in document:” to Enabled.