You can receive e-mails that are not spam but have been labeled as such. In this case we speak of a "false positive".
E-mails that have been falsely detected as spam, can be reported. You are thus helping to refine the detection system.
Send wrongly labeled messages attached to a new post
Send the wrongly labeled message attached to a new post to email@example.com. Enter "ham" as subject for the message.
Note: The reason why the e-mails have to be sent as attachments and can not simply be forwarded, is that when a message is sent as an attachment, the full headers are included. The full headers include routing data which we need to deal with the the message. If forwarded, the message could also be held on its way as being spam.