Remove [JIRA] from email subject lines i.e email prefix in the SMTP Server config

Issue Summary

Currently, it is not possible to remove the ** [JIRA] text from the subject in any Notification sent by Jira

Steps to Reproduce

1. Pull an action to receive an email Notification from Jira
2. See the email received

Expected Results

To be able to remove the [JIRA] text from the subject as in the From value

Actual Results

All Notifications are sent with the [JIRA] text in the Subject:

Workaround

Currently, there is no known workaround for this behavior. A workaround will be added here when available

Original description:

Original Description
Why is it REQUIRED that I enter an email prefix when configuring an SMTP Server for JIRA? Rather presumptuous that all users want this.

For filtering in the email client, all my emails from JIRA are differentiated by the From address. I don't need (JIRA) or anything else prepended to every subject line. And furthermore, now that I can config custom subject lines per email notification type, I could always prepend whatever I want to each subject line in those Velocity templates including "(JIRA)" if I so wanted.

Please remove this requirement from defining the SMTP server.

The problem needs fixing in:

• MailServerActionSupport.java doValidation() – remove check for isBlank(prefix)
• remove "<ui:param name="'mandatory'">true</ui:param>" from updatesmtpmailserver.jsp