OS X Mail Data Detectors - how to format signature

Question

Is there any special formatting to get the data detectors show this banner? (When the contact is not in the address book)

The data detectors seems to find my signature, and when I click the little arrow button offer to add the contact. But the banner seems to appear at random.

Answer 1

From the behavior I see on my system I am going to say it is looking for full signatures in emails that include phone #s and maybe addresses and emails. If it sees changed information then it pops up.

As far as new contacts it seems to look for the same. I have plenty of emails with no phone or email and that never pops up. Or with emails that have just a name and email address where I can get a drop down arrow but the line you have in your question does not come up.