Weird behaviour going on.
Disabled BIND\DNS and sent an email to yahoo. Upon checking the raw headers I got,
dkim=neutral (no sig) header.i=@myDomain.com;
which made me think DKIM was working. So went into Virtualmin >> Email Settings >> DomainKeys Identified Mail which was as before but I clicked on save this time.
I got the following messages,
Finding virtual servers to enable DKIM for …
… no virtual servers with DNS and email enabled were found, but enabling for 1 extra domains
Extracting public key from private key in /etc/dkim.key …
Setting domain and selector in DKIM filter configuration …
Enabling DKIM filter at boot time …
Starting DKIM filter …
Hit Return to DKIM form and then sent another email to yahoo. Checking the raw headers, I get
dkim=pass (ok) header.i=@myDomain.com header.s=mySelector;
which looks like DKIM is working fine without BIND\DNS - you just have to hit save again, if you had BIND\DNS runnning before.
So for anyone wanting to enable DKIM - it looks like you don’t need to enable or have BIND running.
p.s. I reserve the right to alter\retract the last sentence if it all goes weird. LOL