We don’t seem to have a URL for the WP Async Mailer plugin, is there a repo for this somewhere?
Fred, you are right. I never found the time to actually finish that plugin.Basically, what I would recommend to you is to use the code snippet above, add it to your themes’ function.php and you’ve achieved asynchronous sending of emails, which already speeds up things significantly. There are enough mailing plugins out there anyways. The only important feature all of these are missing is being able to switch providers on a recipient-email-basis. As specific regional email providers love to filter out Mailgun/Mailchimp/ and so on IP addresses. The easiest way around that seems to be to use the APIs of Gmail/Microsoft and sending the emails differently for these recipients.
Cool, thanks Erik – and thanks for this really useful set of tutorials!