You are trying to use PressTalk in Workflow. That cannot work. PressTalk only exist in the Design tool.

If you want to do this in Workflow, you need to do this through a script.

Attended that your raw input in previously stored in JobInfo1 and the resulting email will be in JobInfo2:

Code:
var rawInput = Watch.GetJobInfo(1);

Watch.SetJobInfo(2, rawInput+'00000'.substr(1,5-rawInput.length)+'@domain.net');
_________________________
♪♫♪♫
99 frigging bugs in my code
99 frigging bugs
Take one down
Code around
127 frigging bugs in my code
♪♫♪♫