Most internet standards are at http://www.rfc-editor.org/ it will be here somewhere. someone else may be able to advise the specific keywords to use in the search. Here is something from RFC 821: ftp://ftp.isi.edu/in-notes/rfc821.txt which may assist. 4.2.1. REPLY CODES BY FUNCTION GROUPS 500 Syntax error, command unrecognized [This may include errors such as command line too long] 501 Syntax error in parameters or arguments 502 Command not implemented 503 Bad sequence of commands 504 Command parameter not implemented 211 System status, or system help reply 214 Help message [Information on how to use the receiver or the meaning of a particular non-standard command; this reply is useful only to the human user] 220 <domain> Service ready 221 <domain> Service closing transmission channel 421 <domain> Service not available, closing transmission channel [This may be a reply to any command if the service knows it must shut down] 250 Requested mail action okay, completed 251 User not local; will forward to <forward-path> 450 Requested mail action not taken: mailbox unavailable [E.g., mailbox busy] 550 Requested action not taken: mailbox unavailable [E.g., mailbox not found, no access] 451 Requested action aborted: error in processing 551 User not local; please try <forward-path> 452 Requested action not taken: insufficient system storage 552 Requested mail action aborted: exceeded storage allocation 553 Requested action not taken: mailbox name not allowed [E.g., mailbox syntax incorrect] 354 Start mail input; end with <CRLF>.<CRLF> 554 Transaction failed 4.2.2. NUMERIC ORDER LIST OF REPLY CODES 211 System status, or system help reply 214 Help message [Information on how to use the receiver or the meaning of a particular non-standard command; this reply is useful only to the human user] 220 <domain> Service ready 221 <domain> Service closing transmission channel 250 Requested mail action okay, completed 251 User not local; will forward to <forward-path> 354 Start mail input; end with <CRLF>.<CRLF> 421 <domain> Service not available, closing transmission channel [This may be a reply to any command if the service knows it must shut down] 450 Requested mail action not taken: mailbox unavailable [E.g., mailbox busy] 451 Requested action aborted: local error in processing 452 Requested action not taken: insufficient system storage 500 Syntax error, command unrecognized [This may include errors such as command line too long] 501 Syntax error in parameters or arguments 502 Command not implemented 503 Bad sequence of commands 504 Command parameter not implemented 550 Requested action not taken: mailbox unavailable [E.g., mailbox not found, no access] 551 User not local; please try <forward-path> 552 Requested mail action aborted: exceeded storage allocation 553 Requested action not taken: mailbox name not allowed [E.g., mailbox syntax incorrect] 554 Transaction failed [ -----Original Message----- [ From: Michael Shannon [mailto:[log in to unmask]] [ Sent: Tuesday, September 12, 2000 11:04 AM [ To: [log in to unmask] [ Subject: Mail error codes [ [ [ Hello to all... [ [ Does anyone know if there is some sort of a list available [ for mail delivery [ error codes? I know that there's no definitive stadard (yet) [ but surely [ most mail servers use similar codes. I just find it [ difficult to sort out [ what an error might be caused by when all I have is a code without an [ explanation. [ [ I suppose with the sheer number of different [ software/platforms out there [ this may be so much wishful thinking..... [ [ Chazzozz!! [ [ Michael Shannon [ Webmaster [ [log in to unmask] [ [ Note: Views expressed on this list are my own and do not [ reflect the views, [ opinions or position of my employer. [