11px font is OK for your footer section
You're designing a footer area for an email template and a reasonable question pops up in your head. What font size should I use? You also might be questioning what are the good guidelines. A solid way to get some ideas is to find what others do in similar situations. But there's a simpler route. Instead, let me give you just one but convincing example that will provide a safe minimum font size for your footer.
The image above is a footer section of an email I got from Intuit. It's the tax season so I get these pretty often.
Look, taxes are one of the most serious/legal topics for most of us. It's the last thing any one of us wants to screw up. Intuit uses 11px in their footer email section. That makes me think that if the leader in the most serious legal consumer sector uses 11px font, you should be OK with it as well. 11px is still very readable. It's the exact size that if someone wants to read it they will be able to do it. So when you're overwhelmed with options and size recommendations just stick with 11px.