It looks like there is an issue between CA Process Automation 4.3.2 CP01 and CA Process Automation 4.3 SP04 with the operators results.
On that email operator, we don't care whether the operator fails or success before stopping the process so we usually remove both the "Completed" and "Failed" to replace it with a Custom Result with either "true" or "1 == 1" as an expression that we link to the "Stop Failure" operator.
It seems like with CA Process Automation 4.3 SP04, it still tries to go through the "Completed" operator result even though it was removed causing the process to be blocked.
We have also found out that using a custom result for a mail operator with "Process[OpName].Result == 1" as the expression for the only result works.
However, adding parenthesis to get "(Process[OpName].Result == 1)" in the expression does not work.
Release : 4.3.2
Component : Process Automation
Custom exit port issues with 4.3.4 have been resolved in CP01.
When you go to download management and select the product, you have two tabs - the one for Solutions is what you need to select, then select the ITPAM 4.3 product link.
That takes you directly to the published solutions.