A formatted date string can be inserted into a Notification message text box as shown in this example:
The resulting evaluated string would look like this (on May 6th):
Job ran successfully on:May-6-2016
See Also
Appendix I - Formatting Date Strings in EnterpriseSCHEDULE
Date String Format Specifiers
Date String Formatting Examples
Using Date Strings in Variables
Using Date Strings in Jobs