3650264 - Email fail with error code XS838 in SOST when using Zoho mail

• In SOST the error seen is: No delivery to EMAIL@ADDRESS due to problems with system resources - Message No. XS838.
• This does not effect all Email. Some are sent from SAP system successfully while only some email encounter the issue.
• Zoho mail is being used as the mail server.
• Long Text of the XS838 message shows:
  

  No delivery to EMAIL@ADDRESS due to problems with system resources - Message No. XS838

  Diagnosis: The message was processed successfully in the SAP system. An error relating to system resources occurred in a follow-on system. The message was not delivered to the EMAIL@ADDRESS.

  Information from external system (if available)
  ZohoMailHost:Port

  552 5.7.1 The attachments you have added violate the Secure Attachment Policy. <a href=https://www.z

• The SAPconnect trace shows (KBA 1639935):
  
  0102 MAP_SMTP_RESPONSE________________| SMTP Response:
  0103 MAP_SMTP_RESPONSE________________| N REMAIL@ADDRESS C552 M552 5.7.1 The attachments you have added violate the S
  0103 MAP_SMTP_RESPONSE________________| ecure Attachment Policy. <a href=https://www.zoho.com/mail/help/secure-attachmen
  0103 MAP_SMTP_RESPONSE________________| t-policy.html target=_blank>Learn more</a>  TDATA
  0176 MAP_SMTP_RESPONSE________________| EMAIL@ADDRESS: Status set to 838

• SAP Business Technology Platform
• SAP Basis release independent

XS838, C552 M552 5.7.1, The attachments you have added violate the Secure Attachment Policy, Zoho mail, , KBA , BC-SRV-COM , Communication Services: Mail, Fax, SMS, Telephony , Problem