Cannot Receive Emails (Hard Bounces)
If external senders are getting bounce messages when trying to email you, your MX records are either missing, pointing to the wrong place, or not propagated.
Wait for Propagation: If you just changed your DNS records, it can take up to 24-48 hours for global servers to recognize the new route.
1
Verify MX Record Existence
Use an MX Lookup tool to confirm your domain has active MX records. Without them, mail servers don't know where to deliver messages.
$ dig +short MX yourdomain.com
2
Fix RFC Direct IP Violation
MX records must point to a hostname (like mail.domain.com), never directly to an IP address (like 192.168.1.1). If yours points to an IP, change it immediately.
BAD: example.com IN MX 10 192.168.1.50
GOOD: example.com IN MX 10 mail.example.com.
mail.example.com IN A 192.168.1.50
3
Check Port 25 Reachability
Even if DNS is correct, your server's firewall must allow incoming TCP traffic on Port 25 (SMTP). Ask your hosting provider if they block inbound Port 25.
Verified MX points to a valid hostname.
Verified Hostname has an A Record pointing to the server IP.
Verified Port 25 is open on the server firewall.
Emails Landing in Spam
If your outbound emails are successfully sent but land in the recipient's junk/spam folder, it is an Authentication (SPF/DKIM/DMARC) or Reputation issue.
1
Implement SPF (Sender Policy Framework)
SPF tells the world which IP addresses or services (like Google/Outlook) are allowed to send emails on behalf of your domain. Missing this guarantees spam placement.
Type: TXT
Name: @
Value: v=spf1 mx a ~all
2
Fix Multiple SPF Records
You can only have ONE SPF record per domain. If you use multiple services (e.g., Google and Mailchimp), merge them into one.
BAD:
TXT @ v=spf1 include:_spf.google.com ~all
TXT @ v=spf1 include:servers.mcsv.net ~all
GOOD (Merged):
TXT @ v=spf1 include:_spf.google.com include:servers.mcsv.net ~all
3
Deploy a DMARC Policy
DMARC protects your domain from spoofing. Start with a monitoring policy (p=none) to build reputation safely.
Type: TXT
Name: _dmarc
Value: v=DMARC1; p=none; rua=mailto:admin@yourdomain.com;
Outbound Emails Bouncing
If emails you send are returned to you with a "Delivery Status Notification (Failure)" message, you are likely blacklisted or hitting strict server limits.
1
Check RBL Blacklists
If your server's IP address is listed on major Real-time Blackhole Lists (like Spamhaus or Spamcop), receiving servers will block your emails instantly.
Use our 'MX Record Inspector' tool to automatically scan your IPs against global blacklists.
2
Setup Reverse DNS (PTR Record)
Many enterprise servers (like Microsoft 365) will reject emails from IPs that lack a Reverse DNS (PTR) record. The PTR record must resolve back to the hostname specified in your SMTP banner.
Fix: Contact your VPS/Server hosting provider (e.g., DigitalOcean, AWS) and ask them to set the PTR record of your IP to match your mail server's hostname (e.g., mail.yourdomain.com).
Cloudflare DNS Setup Guide
Step-by-step instructions for configuring MX and Email records within the Cloudflare dashboard.
Crucial Cloudflare Rule: Never proxy (orange cloud) your mail server A records. Cloudflare's proxy only supports HTTP/HTTPS traffic, it will block SMTP/IMAP traffic.
1
Add the 'mail' A Record (DNS Only)
Go to DNS > Records. Click "Add Record". Select type "A". Name: "mail". Value: Your server IP. Turn OFF the proxy status (Grey Cloud).
2
Add the MX Record
Click "Add Record". Select type "MX". Name: "@" (Root). Mail Server: "mail.yourdomain.com". Priority: "10".
3
Add the SPF Record
Click "Add Record". Select type "TXT". Name: "@". Content: v=spf1 mx a ~all
cPanel / WHM Setup Guide
Instructions for configuring Local vs Remote mail routing in cPanel environments.
1
Email Routing Configuration
In cPanel, go to "Email Routing". This is the most common cause of cPanel delivery failures.
• If you use cPanel to host your emails: Select Local Mail Exchanger.
• If you use Google Workspace/Office 365: Select Remote Mail Exchanger.
2
Zone Editor (Adding Records)
Go to "Zone Editor". Locate your domain and click "Manage". Click "+ Add Record". Select "MX", set priority to "0", and destination to "yourdomain.com".
GoDaddy DNS Setup Guide
Navigating GoDaddy's DNS management to repair MX issues.
1
Access DNS Management
Log in to GoDaddy. Go to "My Products". Next to your domain, click "DNS".
2
Delete Default Records
GoDaddy often inserts default "Workspace" or "Secureserver" MX records. You must delete these before adding your custom ones, otherwise, emails will be misrouted.
RFC Violations (Direct IP)
Explaining the most common, fatal DNS misconfiguration: The Direct IP MX.

According to IETF RFC 5321 (the protocol that governs email transmission), an MX record must always point to a fully qualified domain name (FQDN), never directly to an IPv4 or IPv6 address. Many strict mail servers will instantly drop connections that violate this rule.

The Wrong Way

Type: MX
Name: @
Value: 192.168.1.100

The Correct Way

Type: MX
Name: @
Value: mail.domain.com

Type: A
Name: mail
Value: 192.168.1.100
Null MX Misconfiguration
Understanding RFC 7505: How to tell the world your domain does NOT accept emails.

If you buy a domain just for hosting a website and have no intention of ever receiving emails on it, you should configure a "Null MX" record. This prevents spammers from trying to bombard the domain and reduces unnecessary DNS lookups.

How to implement a Null MX
To correctly implement a Null MX, the priority must be exactly 0 and the target must be exactly . (a single dot).
Type: MX
Name: @
Priority: 0
Target: .