Ben Bucksch schrieb: > Jay Garcia wrote: > >> X-mailer is a non-standard header entry as opposed to User_Agent. >> > Where is that standard defined? It's not in RF2822. >
aren't they both described in RFC822 ? http://www.ietf.org/rfc/rfc822.txt 4.7.4. EXTENSION-FIELD A limited number of common fields have been defined in this document. As network mail requirements dictate, addi- tional fields may be standardized. To provide user-defined fields with a measure of safety, in name selection, such extension-fields will never have names that begin with the string "X-". Names of Extension-fields are registered with the Network Information Center, SRI International, Menlo Park, California. 4.7.5. USER-DEFINED-FIELD Individual users of network mail are free to define and use additional header fields. Such fields must have names which are not already used in the current specification or in any definitions of extension-fields, and the overall syntax of these user-defined-fields must conform to this specification's rules for delimiting and folding fields. Due to the extension-field publishing process, the name of a user- defined-field may be pre-empted Note: The prefatory string "X-" will never be used in the names of Extension-fields. This provides user-defined fields with a protected set of names. -- Boris
