Abivia participates in a number of programs provided by free mail providers that give us feedback whenever one of their users reports a message that we delivered as spam. Unfortunately, the terms of our agreements with these providers prohibit us from disclosing any details in this feedback to anyone.
When a free mail user reports a message that we sent as spam, it has a negative effect on the reputation of our IP addresses, and this can have a negative impact on the deliverability of legitimate email to other uses of the same platform. For this reason we have to take these reports very seriously. There are two common cases where this comes up.
In the first case, the emails are being forwarded from an address we host to a free mail account. For example we have a user on our system with the address email@example.com that forwards to firstname.lastname@example.org, when someone sends spam to email@example.com that gets through our filters, it will show up in the inbox at firstname.lastname@example.org. When the user reports the message as spam, the free mail host penalizes our IP address, even though we aren't the original source of the email.
In the second case, the free mail user simply doesn't want to hear from the sender anymore. These users, rather than follow an unsubscribe instruction, simply report the message as spam.
Some users seem to not see a difference between "unwanted email" and spam. A message from an "I'm on vacation" auto-responder might not be wanted, but it's hardly spam. If a message like that gets reported as spam, it puts all of our users on the same server at risk of not getting their messages through. Since we're prohibited from discussing this with the free mail user, our only available option is to refuse to send mail to the free mail user who files the report.
If emails are being forwarded to Google Mail, then there is a better approach: set up GMail to fetch mail directly from the Abivia server.
If emails are being forwarded to Hotmail, live.com, Outlook, etc. Then this option isn't available. However you can set up a GMail account and use that to fetch mail from both the Microsoft account and the Abivia account.