Will not email from Zoho Invoice on iPhone

Will not email from Zoho Invoice on iPhone

After creating the invoice and telling the Zoho Invoice APP to email my customer, I receive the error:
The email ID entered XXXXX@xxxxxxx.com is incorrect. Please check and retry.
 
All email addresses are valid. Deleting and re-entering the email does not help.
 
This did NOT used to happen. This function definately worked when I first started using this app.
 
I may try deleting the APP and resintalling to see if it clears it up but I consider that a last resort.
 
Multiple support emails sent, so far no response.
 
Max
eMax IT Services, Inc.