In reply to Jeff Chandler.

@Danny Brown

CASL wouldn't apply in the case of comment approval notification, as it doesn't fit the criteria of a Commercial Electronic Message. And in any case, CASL certainly doesn't require double opt-in. Single opt-in is enough to count as "express consent" and keep you free of trouble.

That being said, it's always best practice to let users know what you plan on doing with their email address, and give them control over the communication that you send them.