Feature request: allow custom DKIM hostname / selector #172

Hello 👋

Currently, when adding a sending domain, the DKIM TXT record hostname/selector is auto-generated (e.g. xxxx._domainkey.example.com) and cannot be customized.
For the Return-Path hostname, we can choose a custom value, which is very helpful.

Request

Would it be possible to:

• allow specifying a custom DKIM selector (e.g. dkim1), or
• allow specifying a full DKIM hostname under _domainkey (e.g. dkim1._domainkey.example.com),

and have the service generate the corresponding DKIM key/TXT value and verify it as usual?

Why

• We configure DNS records for our own users’ domains and want hostnames that are:

  • neutral (not tied to a specific provider),
  • easier to keep if infrastructure changes (only the key/value would need to change, not the hostname).

This is already possible for the Return-Path hostname, and having the same flexibility for DKIM would be extremely helpful.

Thank you very much for considering this 🙏