Description of problem:
Specifying a command to execute after receiving new mail via an automatic check does not work.

Version-Release number of selected component (if applicable):
claws-mail-3.13.2-2.fc24.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Under menu Configuration / Preferences: Under the "Automatic checking" heading, select the "Check for new mail every ..." box, and specify a number of minutes between checks.
2. Under heading "After receiving new mail", select the "after automatic check" box.  {deselect "after manual check" if selected)
3. In the Command to execute specify something like:
notify-send "New Mail" "%d new items"
4.  Wait for new incoming mail to be automatically retrieved

Actual results:
The notify-send command is not executed after new email is automatically retrieved.

Expected results:
The notify-send command is executed after new email is automatically retrieved.

Additional info:
If only "after manaul check" is selected, and mail is manually retrieved, the specified command is properly executed.