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Thread EMail Message-ID length
Tue, Jan 5 2010 4:12 AMPermanent Link

Roy Lambert

NLH Associates

Team Elevate Team Elevate

To allow me to detect duplicate emails I store the message-id in a column of its own. I have this currently defined as VARCHAR(80). I've started to receive some emails with a message-id length of 99 (ridiculous but out of my control). What length do others who store this header separately use ?



Roy Lambert
Tue, Jan 5 2010 4:37 AMPermanent Link

"Raul"
I agree it's bit ridiculous since one should just use GUID in email system
for generating these but in theory email line length can be up to 998 so
nothing illegal about 99. Not sure if you want to go to 998 (or 1000 if crlf
included - looks like you used the suggested line length of 78 + crlf ).

We rarely use the field so in our case we just stuff it into a memo field in
case we need to parse stuff later from it - I know not useful for you.

Raul


"Roy Lambert" <roy.lambert@skynet.co.uk> wrote in message
news:67C72678-DFAC-4EBA-B8DB-AEC8B43833BA@news.elevatesoft.com...
> To allow me to detect duplicate emails I store the message-id in a column
> of its own. I have this currently defined as VARCHAR(80). I've started to
> receive some emails with a message-id length of 99 (ridiculous but out of
> my control). What length do others who store this header separately use ?
>
>
>
> Roy Lambert
>
>
> __________ Information from ESET NOD32 Antivirus, version of virus
> signature database 4741 (20100104) __________
>
> The message was checked by ESET NOD32 Antivirus.



__________ Information from ESET NOD32 Antivirus, version of virus signature database 4741 (20100104) __________

The message was checked by ESET NOD32 Antivirus.

http://www.eset.com


Tue, Jan 5 2010 5:44 AMPermanent Link

Roy Lambert

NLH Associates

Team Elevate Team Elevate

Raul


>Not sure if you want to go to 998 (or 1000 if crlf
>included - looks like you used the suggested line length of 78 + crlf ).

I'm sure - I DON'T Smiley

>We rarely use the field so in our case we just stuff it into a memo field in
>case we need to parse stuff later from it - I know not useful for you.

I only started doing this so that I could check for duplicate emails, before that I just left it in the headers. I've had one suggestion from the Synapse mailing list of using a MD5 hash which I'll investigate to see what the false positive rate is like.

Roy Lambert
Wed, Jan 6 2010 4:30 AMPermanent Link

Uli Becker
Roy,

> To allow me to detect duplicate emails I store the message-id in a column of its own...

I do the same and have a column VarChar(100).
Actually there are a number of records with a lenght of 100.

But why don't you use the GUID instead of the MessageID?

Uli
Wed, Jan 6 2010 7:09 AMPermanent Link

Roy Lambert

NLH Associates

Team Elevate Team Elevate

Uli

>But why don't you use the GUID instead of the MessageID?

I will as soon as you can persuade the rest of the world to use it as well Smiley

I have to work with what's in the emails I receive and over which I have no control.

Roy Lambert
Wed, Jan 6 2010 7:44 AMPermanent Link

Uli Becker
Roy,

> I will as soon as you can persuade the rest of the world to use it as well Smiley

I also wrote my own mail-client and till now there was no provider who
didn't use GUID's.

Uli
Wed, Jan 6 2010 8:34 AMPermanent Link

Roy Lambert

NLH Associates

Team Elevate Team Elevate

Uli

>> I will as soon as you can persuade the rest of the world to use it as well Smiley
>
>I also wrote my own mail-client and till now there was no provider who
>didn't use GUID's.

I think we're talking at cross purposes. From one of the FT emails that's giving me agro:

Message-Id: <12322-844-OZMCDD-KYGZS-6VCYWB-WT8FF-8A5T5P-M-M2-20100105-2c9787c5162d0fc07@e-dialog.com>

This is a 99 characters long GUID ie a globally unique identifier but not a PC/Delphi type GUID and certainly not an ElevateDB GUID (A string value that has an exact length of 38 characters. A GUID value is treated the same as a VARCHAR value.)

The RFC allows for them to be 998 characters long (ie 1000 and exclude the CRLF) and have white space and be wrapped. If you look at the spec in RFC822

4.6.1.  MESSAGE-ID / RESENT-MESSAGE-ID

This field contains a unique identifier  (the  local-part address  unit)  which  refers to THIS version of THIS message. The uniqueness of the message identifier is guaranteed by  the host  which  generates  it.  This 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 should each receive new message identifiers.

It also implies that the uniqueness is specific to a host so you can't just chop the domain part off.

Roy Lambert
Wed, Jan 6 2010 11:47 AMPermanent Link

Uli Becker
Roy,

> I think we're talking at cross purposes.

Yes, I think so. Smile

I know about the Message-ID you are talking about. But I mean the unique
ID that your provider creates for each message in your mailbox:

E.G. a message sent from www.windows-7-forum.net and delivered by
Googlemail:

MessageID of this message in message header:
<20100106125324.a06ced692353@www.windows-7-forum.net>

Unique ID of this message in the mailbox:
GmailId12603b2588700f4e

Here part of a help file:

<<
How to detect which messages are new

The POP3 protocol has no mechanism to determine whether a message has
been already downloaded. Therefore, it's required to keep a list of
identifiers of already downloaded messages in a local database
maintained by your application.

Any time your application searches the mailbox for new messages, it
queries the database for each message in the mailbox to determine if a
message has already been downloaded. If the identifier of the particular
message has not been found in the database, this message is new.

As the message identifier, Unique-ID can be used.

Message's Unique-ID (UID)

Unique-ID (UID for short) is a unique string assigned to each message in
the mailbox. No two messages in the mailbox can have the same Unique-ID
value. Sometimes Unique-ID is called GUID (globally unique identifier).

Unique-ID is not associated with "Message-ID:" header of the message.

POP3 object provides Search method which returns array of Unique-IDs of
all the messages in the mailbox.
>>

Uli
Wed, Jan 6 2010 2:00 PMPermanent Link

Roy Lambert

NLH Associates

Team Elevate Team Elevate

Uli


I don't know where you're getting that from but its nonsense. If you are sent a number of emails from different sources, different email clients, different servers, different ISPs, through different POP boxes the ONLY way you can detect duplicates is information contained in the email. This is the purpose of the Message-ID email header.

This

MessageID of this message in message header:
<20100106125324.a06ced692353www.windows-7-forum.net>

is what is transmitted around and all email clients can access it from where ever it comes

This

Unique ID of this message in the mailbox:
GmailId12603b2588700f4e

looking at it is one applied by GMail and will only be useful if the only place you download from is gmail.

Roy Lambert
Wed, Jan 6 2010 2:15 PMPermanent Link

Uli Becker
Roy

> I don't know where you're getting that from but its nonsense.

What exactly is nonsense for you?

You are right if you really expect the *SAME* message from different
sources, different email clients, different servers, different ISPs. etc.

For me it's important to know which messages have already been
downloaded and which not. In this case the mentioned GUID is the best
way because there is a number of messages with empty Message-ID's as you
cerainly know.

Uli
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