FREQUENTLY BLACKLISTED.

[newera]

We are running Zimbra on a VPS. And frequently blacklisted. Although there is no spamming activity from our mail server. Checked SPF, DKIM, DMARC all seemed OK, increased the TTL values for MX, PTR records. The reason to be blacklisted is that probably the neighbour IPs are spammers. I could not find a solution to this problem.

Moving to another hosting firm is not a solution since many of them on the blacklist already.
Is using a dedicated server can be a solution to this problem or what you suggest?

Regards,

[ianw1974]

Best way, use mxtoolbox: https://mxtoolbox.com/blacklists.aspx

If the blacklists are listing you, you can check the specific blacklists and find out whether the subnet has been blocked which can be common. I had it once a long time ago. In reality, if that is happening, you need to be choosing a more reputable hosting provider. The cheap ones are pretty much almost always problematic since they are abused the most. Some blacklists are worse than others though and sometimes too sensitive to what subnets/IP's that they list.

The link above also has other options you can check/test to ensure you don't have any other configuration issues or something missing that might help. But if it's IP/subnet related, then nothing config-wise is going to solve it until you move away from that ISP/hosting provider. You say most others are blacklisted? Maybe you are looking at the wrong hosting providers?

[newera]

Thank you for your reply, could you suggest a few safe hosting. And is it advantageous to select a dedicated server option?

Regards

[newera]

I re-checked from mxtoolbox and. The subnet has been blocked.

[newera]

Any suggestion about reputable hosting providers.

Regards,

[L. Mark Stone]

FWIW I host on Amazon Web Services.

When you request and obtain a static IP address (called an Elastic IP or “EIP”) you can check its reputation. If it is has a poor one, release it and get another one. Repeat as necessary until you get a clean one.

AWS turn off outbound smtp port 25 now by default. You’ll need to apply for them to turn it on. If your domain has a bad reputation they are recently I am seeing refusing to turn on outbound port 25 and instead requiring you to route your traffic through their SES (“Simple Email Service”).

There are other good hosting providers I am sure.

[ianw1974]

I personally used OVH when I was running my own Zimbra server. Providing you configure the ptr/revdns, etc, there shouldn't be too many problems. From time-to-time some issues did turn up, usually with hotmail/outlook.com. Linode was also good for me when I ran my server there also.

[newera]

Thank you for your suggestions