Closed Dead email domains should not Soft Bounce after DNS failure

[Alpha1]

Affected version

2.3.7

Some prime examples of dead email domains are:
myspace.com (dead since 2009)
viola.fr (dead since 2016)
wanadoo.co.uk (dead since 2017)
orange.net (dead since 2017)
love.com (dead since 2022)

Emails to these dead email domains result in soft bounces, while these should be hard bounces. Of course these are just a few examples and there are thousands of dead email domains that a big board will deal with.

When an email domain has died / gone away, the DNS lookup will fail and this will result in a soft bounce. Yet it should be a hard bounce in most cases.
A very small percentage of such bounces pertains to cases where the email domain is just temporarily offline. Therefore its somewhat logical that this is classed as a soft bounce. Here is an example of the delivery status notification:

Action: failed
Final-Recipient: rfc822; xxx@love.com
Diagnostic-Code: smtp; 550 4.4.7 Message expired: unable to deliver in 840 minutes.<421 4.4.0 Unable to lookup DNS for love.com>
Status: 4.4.7

The impact of this on on sender reputation of such dead email domains can be rather large. Especially for big boards and old boards.
Custom email domains are more likely to go offline over the years.

This issue can be resolved in several ways:

1. Implement a list of dead email domains.
2. Implement a option/setting to always hard bounce DNS failure.
3. HTTP status check on the domain after DNS failure.

If you feel this cannot be addressed as a bug, then please be so kind to move this to the suggestions forum.

 

[XF Bug Bot]

Automated triage: As designed

Thank you for reporting this issue. Bounces are classified by the status code the sending mail server reports. Here it reported a temporary (4.x) DNS failure, which looks identical to a domain that is only briefly offline, so it counts as a soft bounce. Repeated soft bounces still mark the account once the soft bounce threshold is reached. A dead-domain list or an option like this would be a feature suggestion.

This is an automated assessment. A member of staff may review and update it.

 

[Alpha1]

Bounces are classified by the status code the sending mail server reports.

This seems not entirely correct. Or better: incomplete. Bounces are classified by status code AND bounce message. As it should, because status code alone says very little. Xenforo has made many improvements in regards to status messages and this had a major positive impact on correctly classifying bounces. This one is another big one in terms of reducing bounce rate.

Repeated soft bounces still mark the account once the soft bounce threshold is reached.

Only within the 30 day mark or the set limit for the same email address, which is where this functionality fails. If ALL e-mail addresses for a provider fail over multiple months, then there is something else to address than the single email address.

As mentioned in my OP, please be so kind to move this to the suggestions forum.

If you feel this cannot be addressed as a bug, then please be so kind to move this to the suggestions forum.