Multipart/related/mixed/alternative when which Content-Type is better to insert into an email?

Question

Email

I decided to write my own agent for sending (not spam)
Dealing with headers.
I analyzed over 9000 real letters from my mailbox
. I noticed the following trend: the
multi - sport content type in many letters is set quite crookedly
. Maybe spammers are deliberately out of line (in order to more successfully bypass filters?)
Or it’s just that the mailers have straight arms, not really
I would not want to replenish himself an army of cattle-spammers
I want to show off to do everything-by-the-rules.

Can you please tell me which varieties (related / mixed / alternative) should be installed in which cases?
And, also, write a couple of tips about Content--Disposition.

Answer 1

habrahabr.ru/post/17531/
mixed - is used when within one mail message there are several independent and equivalent parts. The simplest example of such a letter is a message with an attachment.
alternative - used when one mail message contains several parts containing the same information intended for display on different client software - for example, a text and HTML version of the same letter.
related - used when one mail message contains several parts that form one final document. A striking example is an HTML letter with pictures. Remember, according to the standard, only in this case should links to the Contend-id of elements (of the form ) work.

Answer 2

It seems to me that the RFC will tell you better than anyone.