Is there any email clients which strip our email headers?

Question

I wanted to know if there's any email clients (e.g. Outlook, etc.) which strip out custom email headers e.g. X-Tallyfy-Y-Z : value

The reason is that I'm adding headers to email so that plugins for Gmail and Outlook can take a certain action if those headers are seen on an email.

In my case, http://tallyfy.com aims to link a "how to" re-usable checklist to an email - so that you can send an email and link a checklist showing how to get something done, right within your email client - with no attachments.

Answer 1

You can access full MIME headers in Outlook by reading the PR_TRANSPORT_MESSAGE_HEADERS property (DASL name http://schemas.microsoft.com/mapi/proptag/0x007D001F) using MailItem.PropertyAccessor.GetProperty.

What exactly makes you think Outlook strips out your headers?