SMTP headers for message-flag in emails

[Guest]

When I use Outlook to send an email with a message flag and a due-by
date/time, I can see that it creates 2 SMTP headers:
X-Message-Flag for the flag, and
Reply-By for the due-by.

But when I send an email via SMTP with both headers, and open the email in
Outlook, the message flag is there, but the due-by is missing. Looking at
the SMTP headers via View >> Options..., Reply-By is not there.

I'm wondering when/how/why the Reply-By header is lost -- by Outlook itself,
or Exchange server, or the SMTP mail gateway?

Any insight is appreciated.

ps: I use Outlook 2003

 

[Sue Mosher [MVP-Outlook]]

I think it's suppressed by Outlook to keep senders from flooding their recipients' mailboxes with unwanted reminder popups.

--
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003

and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers