Communication type & cannot be used

What causes this issue?

Message type &v2& should be sent with communication type &v1&.

System Response

Communication type &v1& is not supported by the conversion module.

How to fix this error?

Use one of the supported communication types:
Printer (LET)
Fax (FAX)
Telex (TLX)
X.400 (X40)
Mail via Internet (INT)
Mail via SAPoffice (RML)

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.