A good question from a reader today who asks, “My client claims you can't have a From: or Reply-To: domain that's exactly the same as your click tracking domain (what Marketo calls the branding domain). Is this true?”
Yep, within the confines of Marketo this is true.
That is, you can't send with the From: header:
From: All Eyez on Me <email@example.com>
and have your rewritten tracked links use the exact same domain:
<a href="https://example.edu/saz95jf81235jhg8712sj">Learn more</a>
You can of course use a subdomain…
<a href="https://click.example.edu/saz95jf81235jhg8712sj">Learn more</a>
… which is what we're used to (branding domains are click-dot-whatever, landing page domains are pages-dot-whatever).
But why? It's not merely a tradition but based on a longstanding technical rule.