...
If you have Gmail configured as your SMTP mail server, you may need to change some settings on your Gmail account.
Enable "less secure" apps. For more information, see this Google documentation on Less secure apps & your Google Account
Unlock your Gmail account:
While you may be able to access your Gmail account, chances are it has been locked for use by third-party apps (in this case, Jira) due to excessive logins. See this Google documentation on unlocking a Gmail account: DisplayUnlockCaptcha
...
The most common error in configuration is that "Null sender" (the default option) is selected. It is suggested to use the "Container sender" as this uses the least amount of system resources. For more information, see this Power Scripts documentation on mail configuration.
Getting support
If these troubleshooting steps do not work, please create a support request on our Power Scripts Service Desk Portal.
...