We have a lot of applications in our onpremises that use email server to send reports etc. 
Now after we moved to Zoho mail we have to change the credentials on this apps to be able to still send their emails . 
If i use and user zoho email account credentials the applications works perfectly.  But is not accepted for security reasons to use any of the Zoho email user account to use his credentials on application settings in our . 

So , what Zoho recommends as optimal solution on this problem ?