Subject: 26.2; Customizing nnmail-expiry-wait-function doesn't work

From: Allen Li <[email-masked]>
Date: Mon, 29 Jul 2019 22:06:30 -0700

Attempting to customize nnmail-expiry-wait-function and selecting a
custom function results in the error:

read: Symbol’s function definition is void: nnmail-

In GNU Emacs 26.2 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.8)
 of 2019-04-12 built on juergen
Windowing system distributor 'The X.Org Foundation', version 11.0.12005000