Thanks, that makes sense. The sending client is a 3G cellular router
(sends me reports on various events), and now I've sent the
manufacturers a query about this problem. I'm guessing that when/if the
message has a Date: field in the header then the discrepancies I'm
seeing in different folders will likely just go away.
The Date: field is a required field in a message and the mail client is supposed to generate it. If the server being used by the sending system is a Mail Submission Agent (MSA) many times the server will add this field. You might try using a different SMTP host setting in the router.
From Wikipedia, the free encyclopedia
A mail submission agent (MSA) is a or software agent that receives electronic mail messages from a mail user agent (MUA) and cooperates with
a mail transfer agent
(MTA) for delivery of the mail. It uses a variant of the Simple Mail Transfer Protocol
(SMTP), as specified in RFC 4409.
Many MTAs act as an MSA as well, but there are also programs that are
specially designed as MSAs without full MTA functionality. Historically
in Internet mail, both MTA (acceptance of
locally-destined mail from other domains) and MSA (acceptance of
submitted mail from local users) functions were both performed by MTAs
using the same protocol (SMTP).
Separation of the MTA and MSA function produces several benefits:
One benefit is that an MSA, since it is interacting directly with the
author's MUA, can correct minor errors in a message's format (such as a
missing Date, Message-ID, To fields, or an address
with a missing domain name) and/or immediately report an error to the
author so that it can be corrected before it is sent to any of the
recipients. An MTA accepting a message from another site cannot reliably
make those kinds of corrections, and any error reports generated by
such an MTA will reach the author (if at all) only after he has already
sent the message.