Issue Summary

This is reproducible on Data Center:yes

Steps to Reproduce

1. Using Active Directory create a user that do not have an email address
2. Give this user role/permission on a Project and make sure he is part of the notification scheme
3. When a notification is trigged for a ticket and this user is part of the notification scheme we see an error on outgoing-mail.log:

   2023-03-23 15:35:52,604-0300 ERROR [] Caesium-1-3 ServiceRunner     [c.a.m.o.c.a.j.p.i.batching.cron.BatchNotificationJob] Exception during sending mail
   java.lang.IllegalArgumentException: 'To' is a required field
       at com.atlassian.mail.Email.<init>(Email.java:55) [atlassian-mail-5.1.2.jar:?]
   

Expected Results

It is possible to have users without an email address, so Jira should better handle this situation and not log an ERROR, but instead a WARN.
Having a way to suppress those messages would be good as well. 

Actual Results

Jira throws an ERROR:

2023-03-23 15:35:52,604-0300 ERROR [] Caesium-1-3 ServiceRunner     [c.a.m.o.c.a.j.p.i.batching.cron.BatchNotificationJob] Exception during sending mail
java.lang.IllegalArgumentException: 'To' is a required field
    at com.atlassian.mail.Email.<init>(Email.java:55) [atlassian-mail-5.1.2.jar:?]

Workaround

No available workaround.