Sending merged mail templates for signatures fail since today

Sending merged mail templates for signatures fail since today

We have ZOHO one, we use merge templates in CRM to edit in ZOHO Writer, and from there send it for signature through zoho sign.

This all worked up until today, suddenly we read in the log that the merge is succesfull but the sending for signature failed.   No reason or cause of the error is mentioned. We are desperate since this is our quote system... We cannot quote our customars now.  

Big FAIL ! This is not the first issue.  I feel i made the wrong deciosion choosing ZOHO for the automatisation of my company....

We are based in Europe!