Create an outbound E-mail as the follow up document
E-mail is a special transaction type in follow up scenario. Only one E-mail transaction type is allowed and special customizing settings are required to use customer's own transaction type.
The customizings are:
1. SPRO -> CRM -> Transactions -> Basic Settings -> Define Transaction Types -> select <Your Transacion Typ> -> click on Assignment of Business Transaction Categories -> select BUS2000126 Businss Activity -> click Customizing header -> change Direction to 1 Outbound
2. SPRO -> CRM -> Basic Settings -> One-to-One E-Mail -> Assign Transaction Types -> change Assign Transaction Types from 0005 to <Your Transaction Type>.
Without the above settings, it is not possible to choose the customer's own E-mail transaction type from the follow up transaction type pop up. The check is performed in class CL_CRM_EMAIL_UTILITY method GET_EMAIL_SETTINGS.