Basic Email Deliverability Checklist: SPF, DKIM, DMARC, and PTR
Quick Summary
If you run your own mail server, correct DNS and responsible sending practices are important for email deliverability.
This checklist covers basic mail server records:
- PTR/rDNS
- SPF
- DKIM
- DMARC
- Mail hostname
- IP reputation
1. PTR/rDNS
PTR/rDNS maps your server IP address to a hostname.
Example:
192.0.2.10 → mail.example.com
The hostname should also point back to the same IP address.
Example:
mail.example.com → 192.0.2.10
2. SPF Record
SPF tells receiving mail servers which IP addresses are allowed to send email for your domain.
Example SPF record:
Type:
TXT
Name:
@
Value:
v=spf1 ip4:192.0.2.10 -all
Replace 192.0.2.10 with your server IP address.
3. DKIM Record
DKIM adds a digital signature to outgoing email.
This helps receiving mail servers verify that the email was sent by an authorized server and was not modified.
DKIM is usually generated by your mail server software or control panel.
Examples of software or panels that may generate DKIM:
- cPanel
- DirectAdmin
- CyberPanel
- Plesk
- Mailcow
- Postal
- aaPanel
4. DMARC Record
DMARC tells receiving mail servers what to do when SPF or DKIM checks fail.
Basic DMARC record:
Type:
TXT
Name:
_dmarc
Value:
v=DMARC1; p=none; rua=mailto:admin@example.com
Start with:
p=none
After testing, advanced users may change the policy to:
p=quarantine
or:
p=reject
5. Mail Hostname
Use a professional hostname.
Recommended format:
mail.yourdomain.com
Avoid:
- random.yourdomain.com
- server123.example.net
- invalid hostnames
- hostnames without A records
6. IP Reputation
Email deliverability also depends on IP reputation.
Avoid:
- Spam
- Purchased email lists
- High bounce rates
- Misleading subjects
- Sudden high-volume sending
- Sending to invalid addresses
- Phishing or suspicious content
7. Test Before Sending
Before sending live email, test:
- SPF pass
- DKIM pass
- DMARC pass
- PTR/rDNS pass
- Mail hostname
- Reverse DNS
- Blacklist status
- Bounce handling
Important
CybroHost provides the server infrastructure. Mail server configuration, mailing practices, bounce handling, sending reputation, and deliverability management are the customer’s responsibility unless managed email service is included.
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