jucker@tis.llnl.GOV (Beat Jucker) (06/05/90)
Can someone please tell me the differences between following protocols: - X.400 P1 - X.400 P2 - X.400 P3 Thanks ------------------ Beat Jucker Tel: +41 33 434868 Anlikerweg 5 CH - 3626 Huenibach Email: jucker@aut.uucp
JPALME@tis.llnl.GOV (Jacob Palme QZ) (06/07/90)
> Can someone please tell me the differences between following protocols: > > - X.400 P1 > - X.400 P2 > - X.400 P3 P1 and P3 are both on the same level, the MTS level of message transfer. P1 is used between two MTA-s and P3 between an MTA and a UA. The information carried in P1 and P3 are very similar, but not always identical. P1 and P3 are often called "envelopes" and contain information needed for the distribution of a message, such as recipient names, routing etc. P2 is a protocol on a level above P1 and P3. P2 information is often called "header". Note that the text on the envelope (P1/P3) is visible to the postmaster, but not the text on the header (P2) inside the envelope. P2 information is only handled by UA-s, MTA-s just transfer it without looking inside. (One exception is that MTA-s can perform character set conversion.) The P1/P3 information changes when a message is transferred from sender to recipient via a number of MTA-s. The P2 information normally does not change (except for character set conversions). Typical information in P2 is Subject, Reply-request etc. Information about the originator of a message can be given in both P1/P3 and P2. The same for information about recipients. If, however, a message is sent to some recipients via MHS, and to other recipients via other means, then P1/P3 may only contain recipients within MHS, while P2 may contain also other recipients. Another difference is that if a message is sent to several recipients, then the message will be split into copies for each recipients by the MTS. When this split is performed, the MTS may (except when a certain flag is set on the message) remove from the P1/P3 information the names of recipients who are not getting this particular copy of the message after the split. Such deletion of recipients is not done on the list of recipients in P2. For those who are accustomed to the Internet mail protocols, P1/P3 approximately corresponds to SMTP, and P2 to RFC822. However, some information which in the Internet protocols are carried in the RFC822 heading, such as "Received by.." fields and "Date", are in X.400 carried on the P1/P3 envelope, not normally in P2.