You can fix this in the Global Domain Document. First, on the Conversions tab, you should set the field "Internet Address lookup" to "Enabled." This way, if it finds the Internet Address field in the person record populated, it will use that value for the display name on outbound messages. This also means you need to have that field populated for all of your users.
Second, still in the Global Domain document, you should set the parameters for if it doesn't find a match or if you have the lookup disabled. The "Local part formed from" field should be "Short name," the "Domino domains included" should be "None," "Domino domain position" should be "Right of '@,'" and "Domino Domain separator" should be "Period."
Finally, you can control if it shows firstname.lastname@example.org vs. John Doe in the recipient's inbox via the Configuration document. On the MIME\Advanced\Advanced Outbound Message Options tab is the field "RFC822 Phrase Handling." The value "Use CN as phrase" makes it appear that the message came from John Doe instead of putting the e-mail address as the value.
This was first published in August 2004