Global21 have you had any joy with this?
Sorry one step I missed would be:
2a. Disable mail 2.
Not sure why you want to have the same email address in To fields on both mail 1 and mail 2?
Hope that helps?
Regards.
The resolution that I found for this was:
1. enable mail 2.
2. copy the <[your-email]> from the “To” field into mail 1.
3. test.
This worked immediately for me. Hope it helps.