要約

Sometimes, the Project admins want their customers to use only the customer portal to raise new requests, but they also want them to be able to add comments using emails.

環境

Jira Service Management Cloud.

診断

At this time, the JSM mail handler does both actions: process an email as a comment or raise a new request based on whether the email is a reference to an existing issue or a new email. There's no way to disable one but leave the other one on. 
We have a few features open looking at the possibility of providing this functionality in the future: JSDCLOUD-1380 - Getting issue details... STATUS  and  JSDCLOUD-1373 - Getting issue details... STATUS

ソリューション

You can try the following workaround in the meantime, however, we cannot guarantee that this will continue to work in the future as we might change the way it works in the future: 

1. Go to your Project → Project Settings → Request Types and click the Create request type button

2. Provide a Name (e.g. New email request), Description, select an icon, and select Emailed request for Use workflow and fields from this issue type

3. Do not select a portal group and click the Create button

4. On the new request form, make sure to add (drag in) the Description field, or JSM cannot add the comments from the email

5. Click the icon in the upper right corner of Jira, click Issues, and then click Field Configuration in the side menu

6. Locate the current field configuration for your project and click the Copy link in the Actions column

7. Click the icon in the upper right corner of Jira, click Issues, and then click Field Configuration Schemes

8. Locate your Field Configuration Scheme for the project and click the Configure link in the Actions column

9. Click Associate an issue type with a field configuration and select Emailed request for the issue type and the copy of your Field Configuration created in step 4 in the Field Configuration drop-down

10. Select your project and go to Project Settings → Fields

11. Click the pencil icon to the right of the Field Configuration copy that is associated with the Emailed request issue type

12. Excluding the fields Reporter, Attachment, Summary, and Description, locate any field in the list that has the screens associated with this project and mark it as required

At this point, you should be able to send a new email to JSM and it will fail to process it. You can then send a follow-up email, including the issue ID in the subject and the email body will be included as a comment in the referenced issue.