Deleted default Mail Server can't be restored - remove option

Summary

Admins have the option to delete a mail Server or mail handler but there is no option to recover the deleted content.

Problem

Customers want to disable incoming mail server so they delete it. There is no option to disable Incoming Email.
https://jira.atlassian.com/browse/JRACLOUD-68296
Note: the global settings at /secure/admin/GlobalMailSettings.jspa only work for other Mail Server and handlers configured.

Customer Impact

They are unable to set incoming email after deleting the default mail server and need to contact support.

Environment

• JIRA Cloud

Steps to Reproduce

1. Navigate to /secure/admin/IncomingMailServers.jspa
2. Delete "POP Mail Server" with "Host: Mailstore"

Expected Results

There is an option to reconfigure the default mail server

Actual Results

There is no option to reconfigure the default mail server. To do so, admins will need to contact support.

Proposed solution

Include an option to disable incoming email and remove the option to delete the mail server and handler

Workaround

To manually restore the Default Mail Server:

1. Click on Add POP / IMAP mail server
2. Enter the information below:
   

   Notes:
   The button Test Connection will throw errors, which is expected.
   The value for username will be jira@<your instance>.atlassian.net.
   The password can have any value.