Complete mail header

Question

I need a set of mail headers to attach to my mail() function in PHP. I send emails with HTML in them, and sometimes services like Yahoo Mail block them. Therefo

Answer 1

The RFCs for both IMF and MIME define the minimal set of headers, so this would be a good place to start.

For IMF, look here: http://tools.ietf.org/html/rfc5322#section-3.6

For MIME, look here: http://tools.ietf.org/html/rfc2045#section-3

Answer 2

    $headers  = "From: testsite < mail@testsite.com >\n";
    $headers .= "Cc: testsite < mail@testsite.com >\n"; 
    $headers .= "X-Sender: testsite < mail@testsite.com >\n";
    $headers .= 'X-Mailer: PHP/' . phpversion();
    $headers .= "X-Priority: 1\n"; // Urgent message!
    $headers .= "Return-Path: mail@testsite.com\n"; // Return path for errors
    $headers .= "MIME-Version: 1.0\r\n";
    $headers .= "Content-Type: text/html; charset=iso-8859-1\n";

Answer 3

The link below could be of some use defining the mandatory headers as:

• Date: The date the message was originated/written.

• From: The person "responsible" for the message.

Answer 4

Most MUA's insert a lot of extra headers; however, here is sort of the bare minimum you can expect.

To: 
Subject:
Date: 
MIME-Version:
Content-type: 

If you using HTML, then you should probably be using multipart messages--but it's not strictly necessary.

Answer 5

When defining if a sender is a possible spammer, many services check if the domain of the sender looks like a dialup user.

Quote from Wikipedia:

One e-mail anti-spam technique: checking the domain names in the rDNS to see if they are likely from dialup users, dynamically assigned addresses, or other inexpensive internet services. Owners of such IP addresses typically assign them generic rDNS names such as "1-2-3-4-dynamic-ip.example.com." Since the vast majority, but by no means all, of e-mail that originates from these computers is spam, many spam filters refuse e-mail with such rDNS names.

Answer 6

Did the mail really come from 'mycompany.com'? I've had problems with some mail services blocking if it didn't really come from the SMTP server that the mail says it does.

A way around this, for me, was making the from to be automail@mydomainnaim.com and adding a reply-to, being the person who sent the mail using my system.