In the commercial voicemail notification module, blank lines left in the GUI in the recipients field are interpreted as null phone numbers and are assigned a priority of zero automatically. Calls are then attempted to the non phone numbers:
pbx_spool.c: – Attempting call on Local/@vmnotify-main for application AGI(vmnotify-main.php) (Retry 1)
chan_local.c: No such extension/context @vmnotify-main while calling Local channel
Not a huge deal except the zero priority means these calls are attempted before legit calls assigned a priority of one, and the timout must be exhausted between each attempt resulting in delays.