It's related to the type of header: SHORTHDR vs SHORTBSMTP. The HDR variants have spelled out 'To:' fields, the BSMTP variants have the generic field. The default for BITNET addresses is HDR since the cost of doing that is fairly low, given DISTRIBUTE and all that. The default for Internet addresses is BSMTP since you'd kill your SMTP server in no time otherwise. But if for any reason it is important to you to have your name in the 'To:' field, you can switch between the options. Eric