Hi! When packet filtering is enabled on our Proxy Server, Listserv via LSMTP cannot send email outside of our domain. The outbound messages gather in the listser/spool folder, but no errors appear in the LSMTP and LISTSERV logs. The Resolver tool in LSMTP can find home.ease.lsoft.com (so it is not a DNS problem), but cannot find the mailer. When I disable packet filtering, outgoing messages are released and the Resolver tool locates both home.ease.lsoft.com and the mail server at that location. All outbound ports are open, but apparently an inbound port on our Listserv server needs to be opened somewhere. Can anyone advise on which port? It seems counter-intuitive since only outbound mail is affected and all outbound ports. Inbound mail to our listserv server is received without problems. Thank you in advance for your assistance. Scott Scott Thomas Head of Information Technologies Scranton Public Library Lackawanna County Library System 500 Vine Street Scranton, PA 18509-3298 Ph: (570) 348-3000 x3026 Fx: (570) 348-3020 Email: [log in to unmask]