To send email using SMTP relay, you configure your application, website, or email client to route outgoing emails through a trusted SMTP server instead of sending them directly from your own server. This SMTP relay server authenticates your request, applies security checks, and delivers your emails to the recipient’s mail server with better reliability, higher deliverability, and lower risk of spam blocking.
Step-by-Step: How to Send Email Using SMTP Relay
Step 1: Choose an SMTP Relay Provider
You can use:
For beginners, a third-party relay is strongly recommended.
Step 2: Gather SMTP Details
You’ll need:
Step 3: Configure Your Application or Website
Below is a generic SMTP configuration example:
This configuration works for:
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WordPress
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PHP mailers
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Python apps
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Node.js
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CRM tools
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Marketing platforms
Step 4: Add Email Authentication (Very Important)
Without authentication, your emails will likely land in spam.
SPF Record
Allows the SMTP relay to send emails on behalf of your domain.
Example:
DKIM Record
Adds a cryptographic signature proving email authenticity.
Provided by your SMTP relay provider.
DMARC Record
Tells receiving servers how to handle unauthenticated emails.
Example:
Sending Email Using SMTP Relay in Popular Platforms
WordPress
Use plugins like:
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WP Mail SMTP
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FluentSMTP
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Post SMTP Mailer
Just enter your SMTP details and test email delivery.
PHP Example (PHPMailer)
Python Example
Common SMTP Relay Errors and Fixes
“Connection refused”
“Authentication failed”
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Wrong username/password
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SMTP auth disabled
Emails going to spam
SMTP Relay vs Direct Mail Sending
Feature
SMTP Relay
Direct Sending
| Deliverability |
High |
Low |
| Setup difficulty |
Easy |
Complex |
| IP reputation |
Managed |
Your responsibility |
| Spam risk |
Low |
High |
| Recommended |
✅ Yes |
❌ No |
SMTP relay clearly wins in real-world usage.
Best Practices for SMTP Relay
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Always use authenticated SMTP
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Warm up new domains slowly
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Avoid spam-trigger words
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Use consistent “From” addresses
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Monitor bounce and complaint rates
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Enable TLS encryption
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Rotate credentials periodically
Is SMTP Relay Secure?
Yes—when configured correctly.
SMTP relay supports:
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TLS/SSL encryption
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Authentication
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IP whitelisting
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Activity logging
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Abuse prevention
It’s far more secure than sending emails directly from unmanaged servers.
Now let’s break this down properly—step by step—so you understand what SMTP relay is, why it matters, and exactly how to use it.
Read More: How to Send Email Using SMTP Relay?
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