Avoiding being labelled as possible spam
I've just had my first "A new reply has been posted on the Forum" email and the "To" address wasn't set so it's come as "To: undisclosed recipients". This is a good marker for possible spam and our filtering software interpreted it as such so perhaps it's something worth addressing? On the same subject (as this something I've had some pain with myself as I run quite a lot of lists on two different software platforms) it would be worth you DKIM signing all your emails as some major spam filters (e.g. gmail) give you credit for doing that. It would also including a text/plain part in all your mails (the account activation email is the one I was thinking of there) as again HTML only is another marker for possible spam. HTH?