I use a unique e-mail address for each web site I login to. This amounts to a few hundred different e-mail addresses all with my custom domain. Where I host my domain forwards all these e-mails to my single Gmail account.

However, Gmail puts all these e-mails in my Spam folder. I gather it does this because the SPF check is failing. I have been marking these e-mails as not Spam for several months but to no avail: they keep going into Spam. 

Is there any way around this?