Posted on /g/ but those idiots deleted my thread cos tech support doesn't belong on a tech board apparently.

Basically, I work for a small company which emails promotional newsletters to customers. Recently, Gmail has blocked all of our emails from reaching people. This is a huge portion of our customers. What is worse, when they place an order, they don't get order confirmations, or dispatch confirmations.

We have contacted people at our hosting provider, at our SEO consultancy, and used the Google forums. Literally no one has been able to come up with a solution. The emails don't even arrive in spam, they just don't turn up. We are all scratching our heads.

So I thought I would ask every tech support forum I can, and that includes you anons.