At HostStage, we have set an outgoing email protection in order to protect our users IPs from being blacklisted.
The protection relies on several metrics which are being introduced in our Mailing Plan guidelines which you can download the PDF directly in the link below :
https://www.host-stage.net/client-area/downloads/14/Mailing-ServersTherefore, if your email server isn't configured properly, or if you are using lists generating bounces, you'll trigger the outgoing protection.
*It is very important that before following the steps to unblock your SMTP ports you fix the issue with the current campaign.
**Also, before unblocking the ports you must clear the mailing queue of your MTA (mail transporter agent) otherwise, the would be blocked again instantly.
There isn't any false positive in the SMTP port block feature.
How does the SMTP block feature is working?
We are analyzing the outgoing emails of your IPs and there is an algorythm giving a score at your mailing content, mailing set up and check whether there are some bounces (undeliverable emails).
If the score is too high on a sample of a hundred emails, it would trigger the SMTP port protection and you'll be receiving an email mentioning the SMTP port has been restricted.
The first step is to analyze your configuration, email content, and the list you are using to send your emails. You can refer to the Mailing Plan Guidelines to help you in your mailing configuration.
If the issue occurs too often, it would involve a unblock cooldown which would prevent you to unblock the SMTP ports time for you to fix the issues with your campaigns.
It would also requires to open a support ticket if the issue occurs too often and we would check your IP blacklists before unlocking it back for you.
How To Unblock Your SMTP Port
1) You would need to go to your client-area and log in. Then, you would need to click on my services from your main dashboard as shown in the pictures below :
2) You would see the list of services you own in a table, you would just need to click on the Linux VPS or the Mailing Server you are sending email with
3) Once you are the service management panel, you may click on SMTP Port Status which would give you the information about each IP on whether the port is blocked or not.
If you do see a "Port Blocked", the text becomes clickage for you to get the output shown below and the ability to unblock the port by clicking the Unblock button.
The Panel you see will give you informations about the issue and even give you a list of emails on which you are facing an issue with which would be an extremely valuable information for you to fix the issue.
The lis of email with problems will for instance give you the remote IP of the ISP involved in the issue.
HINT : You can use this IP to analyze the logs on your end and define what was the issue with your mailing campaign. For instance, if you are using PMTA you can use the following command to get the error logs if any about the IP :
cat /var/log/pmta/* | grep "Destination IP"
-> Destination IP being the IP you took gathered from your SMTP Blocking Info Panel. ie : 18.104.22.168