Posted by J.O. Aho on 09/28/66 11:49

jenngra@gmail.com wrote:
> I am writing an application which shoots out confirmation emails to
> friends and contacts --- and looking at the Beta of Outlook 12 for
> Windows Vista, it looks like it catches this mail as Spam, where-as
> Outlook 2003 and others cleared them just fine. I am also having
> trouble with Yahoo as well. Yahoo and Outlook could just be too
> sensitive, but I am worried some of my mail may not be getting thru.

I think you should ask microsoft what they use to sort mail, as there aren't
much standard in the headers, but it could look something like

Date: Sun, 4 Jun 2006 11:30:48 +0200 (CEST)
From: "User" <user@example.net>
To: anotheruser@example.net
Subject: headertest
Message-ID:
<mailclient.os.majorversion.minorversion.0606041130370.7961@example.net>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed


> This leads me to a question, what are the -basic- things I need in a
> mail() header - so I can feel confident they are all present and
> accounted for, and getting my most systems?

From, To, Subject are a must in a header, anything else is really extra. You
should avoid to copy microsoft type of headers, as these are frequently copied
by spammers and will result in a higher risk for getting filtered away as spam.



> There is an odd checkbox/feature in Outlook 12 - "When sending e-mail,
> Postmark the message to help e-mail clients distinguish regular e-mail
> from junk e-mail".
> Is this a technique that can be used in PHP, and has anyone had any
> success with it?

Sure, it would lessen the risk to be filtered away from the outlook client,
but you won't affect filtering built into MTAs.


Things that triggers spamfilters are HTML code in the mail, specially all
those anchor tags, which spammers uses to fake to where to connect

example: <a href="spammersite.example.net">companysite.example.com</a>

As most people tend to use bad mail clients like outlook, they will only see
the companysite.example.com url and think they will be connecting to the right
place.

Anything extre headers you place instead of the standard headers, place a 'X-'
infront of the header name, example: X-Mailer: PHP



//Aho

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