We've encountered a severe problem with the OOTB email template function in Dynamics CRM 365 Online. Adding "dynamic fields" are not properly replaced with the data in the database records, Pre-existing merge fields work properly but we haven't found a definitive time when they stopped working.
On a template that was last modified in early February, the "Hello again" line was inserted:
Hi {!Contact:First Name;},
Hello again {!Contact:First Name;}
Result being:
Hi Roy,
Hello again {!Contact:First Name;}
I've seen this issue reported on another site but no answers as of yet. I'm hoping the Pro's here will get it resolved quickly.