Yeah, like I said it depends on the configuration of the email server in question. It can also depend on the error in question.
Example: If a GMail inbox is full, it will return a temporary error. If the recipient cleans up their inbox so they have space, your server will try again after 24 hours and this time send the email successfully and GMail reports success.
Example 2: If you send an email to a GMail address that doesn't exist, GMail is set up to immediately return a fatal error and your server does not try to send it again.
Example 3: If you send an email to a custom domain address (like dragonbyte-tech.com) that doesn't exist, and the mail server on that server is not configured correctly, it may return no response or incorrectly return a temporary error. This will cause your server to try again after 24, 48 and 72 hours from the previous attempt at sending the email until it finally gives up.
I checked the settings on your site, and you hadn't filled out the "Bounce Email Address" setting in Email Settings. I filled it out with the same email as you configured for bounced emails, and I'll be testing out the bounced mail handling on your site
I'll post back when I have results for you
