Is it safe to say that the migration of to Office 365 has been mostly completed now? Being a Windows Phone/Windows 10 Mobile owner, I was one of the last to be migrated over due to "special handling" required (and they still broke my Contacts, urrgh).

Anyway, the reason I ask is the there is old email boilerplate code for .ExternalClass and .ReadMsgBody that targeted webmail to fix the container and silly line-height defaults.

.ExternalClass { 
    width: 100%; 

.ExternalClass p, 
.ExternalClass span, 
.ExternalClass font, 
.ExternalClass td, 
.ExternalClass div { 
    line-height: 100%; 

However I'm pretty confident this can be deprecated now, if not entirely removed, unless there is a still an audience yet to be migrated. I'm struggling to find any official information on the migration progress/status from Microsoft on the matter.