Configure PTR, SMTP HELO & SPF
This guide shows how to configure the PTR record (reverse DNS), the SMTP HELO name and an SPF record for your mail server in the PowerPanel, Plesk or Postfix. Together, these three settings ensure that emails from your server are delivered and not marked as spam.
Why Are These Settings So Important?
Modern email providers such as Gmail, Outlook, or Yahoo automatically check incoming emails against several security criteria. If any of these are missing or mismatched, emails will be marked as spam or rejected outright — regardless of their content.
Configure PTR Record & SMTP HELO
The golden rule: The PTR record of your IP and the SMTP HELO banner of your mail server must be identical — and both must point to a custom, non-generic hostname that you control.
A non-generic hostname is a fully qualified domain name (FQDN) that you control yourself — for example mail.yourdomain.com. Generic hostnames provided by a hosting company are treated as a spam indicator by many mail servers. The following should not be used:
| Do not use (generic) | Use instead (your own FQDN) |
|---|---|
| *.startdedicated.com | mail.yourdomain.com |
| *.server4you.com | smtp.yourdomain.com |
| *.serverloft.com | server.yourdomain.com |
| *.dedicatedpanel.com |
Set the PTR Record in the PowerPanel
Navigate to Network → IP Management in your PowerPanel, open the Details of the IP and set the reverse record for your IP to your chosen hostname.
Prerequisite: Before setting the PTR record, an A record for the hostname must already exist pointing to the same IP address. Allow up to 24 hours for DNS propagation.
Configure SMTP HELO
The HELO banner is set on the server itself and must match the PTR record:
myhostname value in the Postfix configuration file:Configure an SPF Record
SPF (Sender Policy Framework) is a DNS TXT record that defines which servers are authorized to send emails on behalf of your domain. Receiving mail servers check this record and reject emails originating from unauthorized sources.
Step 1: Create Your SPF Record
An SPF record is a TXT value in your DNS. Here are the most common configurations:
| Record | Meaning |
|---|---|
| v=spf1 mx -all | Only the mail server defined in the MX record may send |
| v=spf1 a mx -all | The host from the domain's A record and the MX server may send |
| v=spf1 ip4:1.2.3.4 -all | Only a specific IP address may send |
| v=spf1 mx ~all | MX may send; others are marked as softfail (less strict) |
For more complex setups involving multiple providers or external services, use the SPF Wizard to generate a tailored record.
Step 2: Add the SPF Record in the PowerPanel
Navigate to Network → Nameservers → Details for your domain in the PowerPanel and add a new TXT record:
| Field | Value |
|---|---|
| Subdomain | Leave empty (applies to root domain) |
| Type | TXT |
| Target | v=spf1 mx -all |
Step 3: Verify Your SPF Record
After DNS propagation (up to 24 hours), verify your record with the following command:
The output should display your SPF record, e.g. "v=spf1 mx -all".
DKIM & DMARC — The Next Step
PTR, HELO, and SPF are the foundation — but for maximum deliverability and protection against email spoofing, you should also configure DKIM and DMARC. Both are now considered standard practice by most email providers.
Since 2024, Google and Yahoo — and since 2025 also Microsoft for Outlook.com — require SPF, DKIM and DMARC for bulk senders. For regular business domains, both DKIM and DMARC are strongly recommended regardless of sending volume.
Test Everything Together
Once all settings are in place, we recommend running a full email test using a dedicated tool. These check PTR, HELO, SPF, DKIM, DMARC, and other factors in one go:
Further questions about email configuration?
For server infrastructure related issues, our support team is available 24/7 via the PowerPanel ticket system.