> "sender=list" appears to have done the trick (messages are no longer > flagged as suspicious by hotmail). Right -- issues with "On Behalf Of" aside, Sender=List is always your best bet for delivery to Microsoft sites. The reason is that Microsoft's SenderID Framework (SIDF) "improves" (*cough*) upon SPF by taking into account the Sender: and From: headers of a message prior to evaluating the message return path (MAIL FROM). For more information about LISTSERV, SPF, SIDF, and other fun stuff (DomainKeys), see the following paper: http://www.lsoft.com/news/techtipLSV-issue3-2006-us.asp (Footnote 2 talks about the Sender: header and its relationship to SIDF.) For my money, you're usually better off using Sender=List and dealing with complaints about "On Behalf Of" from Outlook users than using Sender=None and dealing with complaints about mail not being delivered to MSN users. Pick your Microsoft-induced poison :) And for the record, Sender=List is the documented default for LISTSERV. -- Liam Kelly Senior Consulting Analyst L-Soft international [log in to unmask] L-Soft is proud to offer on-site or remote Training and Consulting Services. For details, visit <http://www.lsoft.com/products/tcservices.asp>