The Strip Quotes functionality does not work as expected for some email replies

Problem

When using a Jira Service Management Mail Handler (configured in Project Settings > Email Requests) to process incoming emails, the Strip Quotes functionality does not work as expected in some cases.

We found that this bug occurs with a combination of the following factors:

• the email contains both text and html contents
• the html content is is using charset="us-ascii" as the content type
• the "From" header from the email chain is bolded using the formatting below

  <p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US">
  

We suspect that this type of formatting is coming from the Outlook Mail Client.

Environment

• Jira Service Management (JSM) Sever/Data Center 4.0.0 and any higher version
• JSM project using a JSM mail handler configured in Project Settings > Email Requests to process incoming emails

Steps to Reproduce

1. Install JSM on any version 4.0.0 and above
2. Create a JSM project
3. Configure a JSM Mail Handler in that project in Project Settings > Email Requests
4. Raise a request in the project and trigger a notification from that request (by adding a comment for example)
5. Reply to the request using a Mail Client that sends emails in using the "us-ascii" encoding, along with From/To/Subject headers that are bolded using the syntax below

   <p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US">
   

Expected Results

The quoted message will be stripped by the mail handler and a comment will be added to the request without the quoted message:

Actual Results

The quoted message is not stripped by the mail handler and a comment is added to the request including the quoted message:

Workaround

The workaround consists in disabling HTML email parsing:

• Go to ⚙ > Applications > Email Requests
• Go to the option HTML email parsing
• Select No, remove the formatting by converting HTML messages to plain text