If there is one area that regularly throws up questions, it's deliverability. Perhaps some of the specialists can weigh in here...

Text/HTML

1. If you send your email as multipart/alternative and have a text version with wording that differs significantly from the text used in the HTML version, what are the likely deliverability consequences?

I ask because I see many big brand emails where:

    * The text version is just a link to the web version of the email, or
    * Some of the text in the HTML version is "invisible" since it appears as an image. So the text and HTML versions are similar when viewed by a human, but won't appear similar to a piece of software trying to "read" the text.

Are these brands making deliverability mistakes, or do they know something I don't? I'd always assumed this would lead to a higher spam score in, for example, SpamAssassin?

(N.B. Using images to display text also causes problems when images are blocked.)

2. Is there any deliverability penalty if you send just an HTML email but coded as text/html rather than multipart/alternative?

(Ignoring the question of whether you'd want to!)
Reputation and links/images



"...some receivers auto-enable images and links for the highest reputation senders."

I know that certain email certification programs have this benefit at selected ISPs. But...

3. Are there any ISPs where a solid reputation (but no certification) means your images and links are automatically enabled?

If so, this would add more weight to the argument that deliverability tactics are not just about getting email delivered.