I have a few functions that get triggered by email filters.  All of the functions with SendMail have stopped working.  They all have been working fine for a few years then suddenly stopped working about 2 weeks ago. 

Tried emailing support but haven't received a reply.

They're pretty basic so don't know what is going wrong.  The filters appear to be logging correctly but nothing gets sent.

Example function:

sendmail
[
    from :zoho.adminuserid
    to :"XXXXXXXXX@gmail.com"
    subject :"Test"
    message :"Email"
]

The "Test Run" button doesn't work either. 

Any help would be greatly appreciated.