Voicemail email address corrupt when message is in the process of being recorded during reload

I have been testing a custom script today which has involved a lot of reloads and came across the following situation (the script I have been testing has nothing to do with email or anything that would affect the below):

When someone is in the process of leaving a voicemail and Asterisk is reloaded when they hang up after the reload the email that it generated has a corrupt To: field or not sent at all.

The Postfix log contains the corrupt address which is direct from Asterisk and looks similar to this:

to=<P??$3?@mydomain.com>

I think this is more of an Asterisk bug than FreePBX but would like to hear if anyone else can replicate.

Running deliberate tests here just now has not yielded the corrupt To address but I have found that it does not send the email at all. After a reload when the person hangs up asterisk ends with 'User hung up' and no email is generated.

I am running Asterisk 11.13.1