Steps to reproduce:

1. Create SMTP mail Server
   2. Setup POP/IMAP mail server and a create a new issue or add a comment to an existing issue mail handler and check the CC Watchers field
   3. Send an email with the cc field to some other email address(which the user is register in JIRA) to the mail server and JIRA expectedly create a issue from it and added cc field email address into watchers of that issue.
   4. After that, if continue to reply that email it will actually comment on that issue however if the cc field of the mail address is added some other email address, it won't add those email address as watchers.

Use case:

1. We are currently using JIRA as a CRM tool and as a result we want to quickly loop in other JIRA users onto a ticket for visibility and response
2. However with the current setup this is not possible and if the team is travelling, they are not able to access JIRA without being on VPN to add addtional watchers.