Yeah, your mail provider is one of the ones that's really prone prone to thinking comment notifications are spam and dumping them in the spam folder. There is, sadly, only so much we can do about it on our end (and we have done what we could) but you can work around it by specifically adding dw_null@dreamwidth.org to your contacts, and if that doesn't work, set up a recipe to automatically put mail sent from dw_null@dreamwidth.org in a separate subfolder (since it thinks that anything you have a recipe for is automatically wanted mail).