[UA-EAI] New email app

[Arnt Gulbrandsen]

It was I who did it.

It is a matter of experience and a number of 
simple checks. You connect to the SMTP server, notice the version and 
know whether that supports EAI. (In this case it does: I wrote that.) 
Find out what framework is being used (there is a tool called builtwith 
that helps), and know that framework and the culture around it well 
enough to guess what versions of what libraries are needed. (In this 
case, they use Ruby, Rails, Actionmailbox and Mikel-Mail, which got EAI 
support in 2017.)

It is the kind of thing that is simple with 
expertise, but a little difficult to nail down. You just look at it and 
recognise it, sort of.

My guess is that they're missing EAI support in 
the spam filter, and that's all. But I can send mail and find out when 
I am back at my desk in a few days.

Arnt