[enhancement]: Fix default SMTP banner to improve SMTP server reputation

[nickspring]

Which feature or improvement would you like to request?

I'd like to see this feature:

Right now default banner in SMTP is:

220 Stalwart ESMTP at your service

However is crucial (for SMTP server reputation and validations) to have here hostname:

220 your_hostname.com Stalwart ESMTP at your service

Without this all smtp validators warns:
"Reverse DNS does not match SMTP Banner"

Is your feature request related to a problem?

No response

Code of Conduct

• I agree to follow this project's Code of Conduct

[williamdes]

See #119

[nickspring]

Yes, but it's about changing banner. Yes, I changed it, but not each user knows about this validation. It will be better to have it by default.

[helmut72]

Can this be still overwritten? Hostname of the server isn't always the DNS record. Also hostname doesn't resolve always with FQDN, but with hostname only (without domain part).

[mdecimus]

Yes, only the default value for the greeting was changed. It uses the function key_get('default', 'hostname') which expands to the system's hostname defined in lookup.default.hostname.