IP reputation: why cheap hosting blocks your mail
The problem
"We do everything correctly, yet our mail doesn't arrive with certain recipients." That's a classic case of poor IP reputation. You notice it in messages that disappear without a bounce, in clients at large mail providers who receive nothing, or in a notice that your IP address is on a blocklist.
The frustrating part: you're often not to blame at all. If you send via cheap, shared hosting, you sit on the same IP address as dozens of other customers. If one of them behaves like a spammer, the whole address gets a bad name, and you're sending under that same flag.
Why does this happen?
Receiving servers keep track of how an IP address has behaved in the past. If a lot of spam came from it, if mails were often marked as unwanted, or if it was on a blocklist, trust drops. That trust helps determine whether your message reaches the inbox.
A few causes that lower the reputation of a sending IP:
- Shared hosting. You inherit the behaviour of everyone sending from the same IP address.
- Blocklists. If the IP address ends up on such a list, many recipients refuse everything coming from it.
- Sudden volume spikes. Hundreds of mails at once from an address that normally sends little looks like a hijacked server.
- No monitoring. No one notices the reputation deteriorating, so no one intervenes.
Important: reputation is tied to the IP address and to your domain. Even with a clean domain, you ride along on the reputation of the IP address you send from. Conversely, on your own, clean sending IP you build up a clean history, which makes recipients trust you more and more. So reputation isn't a snapshot, but something you build up or break down.
IP reputation often goes hand in hand with authentication and reverse DNS. If you want the full picture, read why your mail ends up in spam.
How to solve it
You can't "talk your way out of" IP reputation with a bit of text; it comes down to where you send from and how that server is managed. That's largely the work of your provider.
What you can do yourself:
- Only send to people who expect your mail, and keep your lists clean.
- Build up larger mailings gradually instead of in one spike.
- Occasionally check that your sending IP isn't on a known blocklist.
What a good provider carries:
- Sending via IP addresses with a good, established reputation.
- Actively monitoring that reputation and intervening if something changes.
- Correct reverse DNS and authentication, so the IP address radiates trust.
This is at once an important difference between running your own mail server and using hosted email. Managing a server yourself also means building up and monitoring the IP reputation yourself, watching blocklists and intervening if something goes wrong: work that never stops. With hosted email that lies with a party that does it for many customers at once. The trade-offs involved are in own mail server versus hosted email.
Checklist: IP reputation in order
- You don't send via a generic, shared cheap IP address with unknown neighbours.
- Your sending IP is on no known blocklist.
- Reverse DNS (PTR) and authentication are correctly set up.
- Your lists are clean and you only send to those who expect your mail.
- You build up larger mailings gradually.
- Someone monitors the reputation and intervenes when there are problems.
How Mailflux handles your IP reputation
At Mailflux you don't have to tinker with IP reputation yourself. We run the sending servers, monitor their IP reputation and ensure correct reverse DNS and managed SPF, DKIM and DMARC. That way you don't send from a random shared address with unknown neighbours, but via infrastructure built for deliverability.
Every plan moreover filters with machine learning against spam, phishing and malware, with standard antivirus, antispam and antimalware, automatic backups and optional two-factor authentication. You get professional email on your own domain, hosted in Europe and GDPR compliant.
FAQ
Frequently asked questions
What is IP reputation in email?
It's the reputation of the IP address you send from, built up from how that address behaved in the past. Receiving servers use that reputation to decide whether your message reaches the inbox, goes to spam or is rejected.
Why does cheap hosting block my mail?
On cheap, shared hosting you share an IP address with many other customers. If one of them behaves like a spammer, the whole address gets a bad name and you inherit it. Your mail is then blocked or treated as spam, through no fault of your own.
How do I know if my IP is on a blacklist?
There are free checking services where you can look up an IP address on known blocklists. If you're on one, that's often hard to solve yourself on shared hosting. A provider that manages the sending servers keeps an eye on this for you.