Why does Gmail hate my domain?

I've had similar problems over the last year or two with Gmail and with Outlook/Live Mail.

Our 2 person small time company sends a few hundred mails a month at most. We replay to someone on Gmail and get spam-binned. They whitelist us, we reply again and get spam binned. We send the mail via a major provider and it gets through.

On Outlook a website mail form sending emails to a hotmail.co.uk address was getting blocked - the server has the same IP it's had for years, the form has been used for years, the recipient has whitelisted the email address. I forget what eventually fixed it, think it was addition of a reply-to address; quite ridiculous.

In both cases they are long term domains with real ID info that hasn't changed, the domains have been on the same IP held by the same ISP for at least 3 years and owned by the same owner used for the same businesses for at least 10 years. Both domains are long-term registered in (Google|Microsoft) analytics.

Yes I can see that such domains could be purchased by spammers and the prior owners may not change their ID info and the new holders may be able to purchase space on the old server and so keep the IP address (despite the established ISP having strong anti-spam policies) and may be able to then send out spam emails, but who would whitelist those emails???

IMO on either Outlook or Gmail if you whitelist something, even if it were spam from a known spammer, then they should let it through (sanitised if needs be). If they wanted to they could add a "99.999996% of others blocked this but you have whitelisted it, do you want to block emails from YourBestFriendWhoSendsSpam@theirISP.com in the future?".

/rant

(There's a minor typo in your website: SMPT should be SMTP)

thanks! fixed!

It is a problem with the policies of your company. I don't know why they should have blacklisted our site, maybe they want to be sure that your email are managed by them :)

If you are curious, try to go on our italian website: qboxmail.it

While I don't doubt this, I often see from DIY types some really lazy smtp habits. If they don't have their reverse DNS matching the forward DNS as well as the HELO name matching that as well, then, yes, that will be a major red flag for anti-spam systems. Reverse DNS is pretty important and weighed heavily.

smtp delivery is something of a black art, but at the very least those things need to be set correctly. Its also worth mentioning that if you have 'spammy' applications that opt people in to mailings then a lot of people just get pissed off and click the 'junk' button over and over instead of unsubscribing properly. So think twice before auto-subing customers or enabling 'mail me replies' by default on forums and such.

I also learned the hard way that once you're on Cisco Ironport's spam list, then you really can't get off. There's no one to talk to. Its supposed to be automated. In practice, that means months before your domain is unblocked. I find most Ironport admins just use that sole list even while Cisco recommends they use many and weigh the average. After a stupid config change that opened our smtp to relaying, we got off everyone's blacklist but IronPort. IronPort is pretty much the defacto standard in several types of enterprise. My fix? Get a different IP address for the mail server.