ZmMailList is not Defined . Mail tab disabled

[DEREKB]

Hi,
We have a number of users for which the Mail feature/tab is disabled in the COS or individual mailbox. Since upgrading to version 5.12 this causes the Briefcase to become inaccessible as it throws up an error and doesn't display the briefcase menu-tree or contents. Screenshot attached. I've upgraded to 5.13 and problem still exists. There error did not happen is version 5.02

I assume it's due to some code not being loaded into the ajax interface because the mail tab isn't loaded . Has anyone else noticed this ?

Is there a quick fix or should I report it as a bug ?

Thanks,
Derek.

[Emanuele Aina]

Same here on version 5.0.13_GA_2791.DEBIAN4.0.FOSS.

The only solution I've found is the one suggested in the OP, so I've re-enabled the mail panel even if we'd like to leave it disabled.