Secondary Domain

What is a Secondary Domain?

A secondary domain (also called a cold email domain or sending domain) is a separate email domain used specifically for outbound sales and marketing emails, distinct from your primary corporate domain.

Example:

• Primary Domain: company.com (for all business operations)
• Secondary Domain: getcompany.com or company-mail.com (for cold outreach)

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Why Use a Secondary Domain?

Protect Primary Domain Reputation

The Risk:
Cold email has inherently higher bounce rates, spam complaints, and lower engagement. If these activities damage your primary domain's sender reputation, ALL company emails (including customer communications, internal operations, and transactional emails) suffer.

The Solution:
Use a secondary domain for risky outbound activities. If deliverability issues occur, only the secondary domain is affected.

Faster Recovery from Issues

Primary Domain Problem:

• Hitting spam traps or getting blacklisted affects entire company
• Recovery takes weeks or months
• Business disruption across all functions

Secondary Domain Advantage:

• Problems are isolated to outreach activities
• Can quickly spin up new secondary domain
• Primary domain operations continue unaffected

Testing and Experimentation

Use Cases:

• Testing new email strategies
• A/B testing subject lines and content
• Targeting new markets or segments
• High-volume campaigns

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Setting Up a Secondary Domain

1. Choose the Domain Name

Best Practices:

• Keep brand connection clear (getcompany.com, trycompany.com)
• Short and memorable
• Avoid hyphens and numbers
• Professional appearance

Examples:

Primary	Secondary Options
---------	-------------------
acme.com	getacme.com, acme-mail.com, helloacme.com
startup.io	trystartup.io, startup-mail.com

2. Technical Configuration

Required DNS Records:

SPF (Sender Policy Framework):

getacme.com. IN TXT "v=spf1 include:sendgrid.net ~all"

DKIM (DomainKeys Identified Mail):
Generate keys through your email service provider and add CNAME records.

DMARC:

getacme.com. IN TXT "v=DMARC1; p=none; rua=mailto:dmarc@getacme.com"

3. Email Service Provider Setup

Configure:

• Add secondary domain to your ESP (SendGrid, Mailgun, Amazon SES)
• Verify domain ownership
• Set up dedicated IP if volume warrants it
• Configure tracking and analytics

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Secondary Domain Best Practices

1. Warm Up Properly

Even though it's a secondary domain, proper warm-up is essential:

Week 1-2: 10-20 emails/day
Week 3-4: 20-40 emails/day
Month 2: Scale to target volume

2. Maintain Brand Consistency

From Address Examples:

• name@getacme.com
• name@acme-mail.com
• name@helloacme.com

Email Signature:
Include full company details to maintain legitimacy:

John Smith
Sales at Acme
www.acme.com | 555-123-4567

3. Monitor Deliverability

Track Metrics:

• Open rates (should be 20%+)
• Reply rates (should be 5%+)
• Bounce rates (should be <2%)
• Spam complaints (should be <0.1%)

4. Rotate When Needed

When to Use New Domain:

• Sender score drops below 70
• Blacklisted on major providers
• Consistently poor deliverability despite best practices

Rotation Strategy:

• Maintain 2-3 secondary domains
• Rotate based on performance
• Retire damaged domains, start fresh

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Common Mistakes

1. No Brand Connection – Domains like xyz-cold-mail.com look spammy
2. Skipping Warm-Up – Sending volume immediately damages reputation
3. Poor Authentication – Missing SPF/DKIM/DMARC causes filtering
4. Ignoring Metrics – Not tracking deliverability until problems occur
5. Domain Exhaustion – Burning through domains without addressing root causes

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Primary vs Secondary Domain Comparison

Aspect	Primary Domain	Secondary Domain
Purpose	All business email	Cold outreach only
Risk	Low (warm leads, customers)	Higher (cold contacts)
Reputation Impact	Affects entire company	Isolated to outreach
Recovery	Difficult, slow	Easy, replaceable
Cost	N/A (already owned)	$10-15/year per domain

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Key Takeaways

• Secondary domains separate cold outreach from primary business email
• Protects primary domain reputation from cold email risks
• Setup: choose domain name, configure DNS, add to ESP
• Warm up properly even for secondary domains
• Maintain brand consistency in naming and signatures
• Monitor deliverability metrics continuously
• Rotate domains when reputation is damaged
• Avoid common mistakes: no brand connection, skipping warm-up, poor authentication