Mercury 4.73, containing this fix and a number of other updates, is now being prepared, and should be released shortly.

/Rolf

Big picture is I am trying track why some of my emails are going missing. This has lead to some detailed traces and now I have a question around the Message-ID headers generated by Mercury.

I am using Mercury to forward email as an SMTP relay engine. The traces to my downstream Smarthost (Exchange) show for example a single SMTP session with the Smarthost being used to transmit 3 emails all to the same recipients but with 3 differing Subjects and content. The Mercury generated Message-ID header for each email in the session is the same. Is this legal/normal? Shouldn't each email have its own id or is the ID somehow linked to the session/socket and it is fine to have duplicates?

Peter

afaik, the message-ID only needs be unique within a maildrop, not in transit, and it's the server responsible for the maildrop to keep the messages apart.

I am using Mercury to forward email as an SMTP relay engine. The traces

to my downstream Smarthost (Exchange) show for example a single SMTP

session with the Smarthost being used to transmit 3 emails all to the

same recipients but with 3 differing Subjects and content. The Mercury

generated Message-ID header for each email in the session is the same.

Is this legal/normal? Shouldn't each email have its own id or is the ID

somehow linked to the session/socket and it is fine to have duplicates?

 The RFC 2822 message header Message-ID: is a unique header in the message.  The Mercury message ID shown in the logs should be unique within a session.

So it appears this is a bug in Mercury 4.72. I know for a fact the Exchange server will discard what it thinks are duplicate messages since this is discussed a lot on various forums. I have since taken Mercury out of the loop and my missing email problem has cleared up.

 To recreate this problem; have a dumb SMTP client send a large number of small messages without any message-ID headers to Mercury. Mercury will relay to a smarthost giving many of the outgoing messages the same message-id header. Exchange will then randomly drop some of them without notification.

I have been scratching my head for weeks on this.

 Peter Dunphy

RFC2822  - It appears that Mercury 4.72 violates the RFC:

The "Message-ID:" field provides a unique message identifier that
   refers to a particular version of a particular message.  The
   uniqueness of the message identifier is guaranteed by the host that
   generates it (see below).  This message identifier is intended to be
   machine readable and not necessarily meaningful to humans.  A message
   identifier pertains to exactly one instantiation of a particular
   message; subsequent revisions to the message each receive new message
   identifiers.

So it appears this is a bug in Mercury 4.72. I know for a fact the

Exchange server will discard what it thinks are duplicate messages since

this is discussed a lot on various forums. I have since taken Mercury

out of the loop and my missing email problem has cleared up.

 To

recreate this problem; have a dumb SMTP client send a large number of

small messages without any message-ID headers to Mercury. Mercury will

relay to a smarthost giving many of the outgoing messages the same

message-id header. Exchange will then randomly drop some of them without

notification.

I have been scratching my head for weeks on this.

This has been verified and passed to the Mercury test group and David.  Any time you are using a dumb  mailer the Message-ID: will be duplicated when sending in the same session.

This has been verified and passed to the Mercury test group and David. 

Any time you are using a dumb  mailer the Message-ID: will be duplicated

when sending in the same session.

Regarding "same session"  and dumb mailers (like aspSmartMail). Would this vbscript code send mail in one or two sessions? Or, what defines a session when sending using a dumb mailer? Is it the creation of the aspSmartMail object or calling its SendMail method? 

<%
obj = CreateObject("AspSmartMail.SmartMail")

obj.SenderAddress = "someone@domain.com"
obj.Recipients.Add "john.doe@domain.com", "John DOE"
obj.Subject = "Hello John"
obj.Body = "Dear John,..."
obj.SendMail

obj.Recipients.Clear
obj.Recipients.Add "kees.visser@domain.com", "Kees Visser"
obj.SendMail

set obj=Nothing
%>

 This would definitely be 1 session:

<%
obj = CreateObject("AspSmartMail.SmartMail")

obj.SenderAddress = "someone@domain.com"
obj.Recipients.Add "john.doe@domain.com", "John DOE"
obj.Recipients.Add "kees.visser@domain.com", "Kees Visser"
obj.Subject = "Hello John"
obj.Body = "Dear John,..."
obj.SendMail

set obj=Nothing
%>

Is the fix on 4.72 available?