For HTML email, you need to write HTML like in 1999.
This use of "article" will break in many many email clients:
https://github.com/hasadna/OpenCommunity/blob/master/src/communities/templates/emails/_protocol.html#L80
Also other things, like use of "h" tags (e.g.: "h1") can be problematic because of the ways that some clients (hotmail, live and outlook.com in the case of "h" tags) apply their own styling.
There are many places to find out about the intricacies of HTML in email, but this is probably the best place to start:
http://htmlemailboilerplate.com/
For HTML email, you need to write HTML like in 1999.
This use of "article" will break in many many email clients:
https://github.com/hasadna/OpenCommunity/blob/master/src/communities/templates/emails/_protocol.html#L80
Also other things, like use of "h" tags (e.g.: "h1") can be problematic because of the ways that some clients (hotmail, live and outlook.com in the case of "h" tags) apply their own styling.
There are many places to find out about the intricacies of HTML in email, but this is probably the best place to start:
http://htmlemailboilerplate.com/