I ran into this today and wanted to share it. I was making an email blast to go out and using the usual HTML5 Email Boilerplate to do it. The benefit of this is you get far more control over your designs then using something like Mailchimp to do it. It’s not easier then Mailchimp, but you can be more creative.
So, I tested my design in Litmus and noticed that the paragraph spacing was non existent in Yahoo Mail. There was no margin between the paragraphs. I quick google search later and I found that back in 2008 Yahoo dropped support for it by default.
“Well, Jason, what’s the fix,” you ask?
Simple, just add margin-bottom: 1em inline or in your emails stylesheet. That’ll fix that.