If you are using the web api implementation for Amazon SES / Mandrill / Mailgun / etc and you find out that bounce processing doesn’t really work, below are potential reasons:
1. You are redirecting users from http to https.
If that’s the case make sure the /dswh/ uri is not included in your redirection rules to https, basically each request that comes to http://yourdomain.com/index.php/dswh/X must be left untouched, without redirecting it to https://yourdomain.com/index.php/dswh/X
In case it is unclear, http://yourdomain.com/index.php/dswh/X is the url format where wen notifications are sent by amazon/mandrill/mailgun/etc to notify MailBul about bounces/complaints and so on.
[Additions will be made as we find out more reasons]