We are running LISTSERV 15.5 and lately I have noticed on a number of lists a "550 No such list." error. One thing in common is the use of a HEX name, like 2.0006194D at a LISTSERV address (see example below). Since we aren't sending email to these addresses, where do they come from and is there an easy way to block them without disrupting "normal" LISTSERV "network" activities? -Rich -- Richard A. Helmke Internet: [log in to unmask] Assoc Prof, Computer Science [log in to unmask] System Manager, Technical Services Voice: 708-209-3221 Concordia Administrative Information Systems Fax: 708-209-3177 River Forest, IL 60305-1499 -----Original Message----- From: CAIS/CUS LISTSERV Server (15.5) [mailto:[log in to unmask]] Sent: Wednesday, November 19, 2008 12:01 AM To: POSTMASTER Subject: XXXXXX: Daily error monitoring report The following X subscribers are currently being monitored: Err First Last Address --- ----- ----- ------- 1 11/05 11/05 [log in to unmask] Last error: 5.1.1 Mailer [127.0.0.1] said: "550 No such list." 1 11/09 11/09 [log in to unmask] Last error: 5.1.1 Mailer [127.0.0.1] said: "550 No such list." 1 11/18 11/18 [log in to unmask] Last error: 5.1.1 Mailer [127.0.0.1] said: "550 No such list." 1 11/09 11/09 [log in to unmask] Last error: 5.1.1 Mailer [127.0.0.1] said: "550 No such list." Err= Number of delivery errors received thus far First= Date first delivery error was received (mm/dd) Last= Date of most current delivery error (mm/dd) Subscribers will be automatically deleted from the list when delivery errors have been reported for a period of 14 days or more, or when 4 delivery errors have been received, whichever occurs first. Monitoring will cease after 15 days without any reported errors. Note: Manually deleted subscribers may remain on the monitoring report under an alias address. Such entries will expire eventually. You do not need to do anything about them.