rocky
Here's some steps how to achieve what you want. Remember, this just what I thinking from my side, so you can try it first. Remember to backup your server / snapshot before try this one:
The error you're seeing is likely due to a mismatch between your mail server's PTR record (reverse DNS) and forward DNS (A record). Gmail and other email providers check that these records match as a way to verify the identity of the sending server, which helps prevent spam.
Here's how to troubleshoot and fix the issue:
Step 1: Check Existing PTR Record
Find Your IP Address: First, confirm the IP address of your mail server (e.g., 203.0.113.25).
Check the PTR Record: Run the following command in the terminal or use an online tool to verify the PTR record for your IP address:
dig -x your.server.ip
Or, use nslookup:
nslookup your.server.ip
This should return the hostname associated with your IP (e.g., mail.yourdomain.com). If it doesn't return anything, the PTR record may not be set correctly.
Verify the Hostname from the PTR Record: Confirm that the hostname returned by the PTR record (if any) is the one you’re using as your mail server’s identity. For example, if your mail server introduces itself as mail.yourdomain.com, then the PTR record should resolve to that hostname.
Step 2: Ensure Forward DNS (A Record) Matches the PTR Record
For Gmail to recognize the PTR record, the forward DNS (A record) for the hostname in your PTR record must match the IP address. Here’s how to check this:
Check A Record for Hostname: Using the hostname from the PTR record (e.g., mail.yourdomain.com), check the A record:
dig mail.yourdomain.com
This should return the IP address of your mail server (e.g., 203.0.113.25).
Confirm the Match: Verify that the IP address returned by the A record matches the IP address of your mail server. If it doesn't, you’ll need to update the A record.
Step 3: Request PTR Record Update from Your Provider (If Necessary)
If the PTR record isn’t configured correctly (or at all), you’ll need to request a change from your hosting provider or ISP, as PTR records for IP addresses are managed by the provider.
Contact Support with a Specific Request: In your support ticket, request that the PTR record for your IP address 203.0.113.25 be set to mail.yourdomain.com (replacing this with your actual server hostname).
Wait for Confirmation: Providers sometimes take a few hours to propagate DNS changes. Once the change is confirmed, test it again using the dig -x command or nslookup.
Step 4: Confirm with Gmail Postmaster Tools (Optional)
If your IP and domain are properly configured but still experiencing issues with Gmail, consider setting up Gmail Postmaster Tools for your domain. This tool provides detailed information about Gmail’s view of your domain’s email traffic, authentication, and deliverability.
Example of the Correct Setup
For Gmail to accept your emails:
- PTR Record for
203.0.113.25 → mail.yourdomain.com
- A Record for
mail.yourdomain.com → 203.0.113.25
When both records match as shown above, Gmail will see this as a valid configuration.
Step 5: Test Email Delivery Again
After confirming the DNS records, test sending an email to a Gmail account. If the configuration is correct, Gmail should no longer reject your messages with the PTR error.
