Welcome to GrowhtHub Knowledge Base Hub
Welcome to GrowhtHub Knowledge Base Hub
Why Emails Get Marked as Spam (and How to Fix It)
Mailbox providers use many signals to decide whether an email belongs in the inbox or the spam folder. Below are the most common reasons emails are flagged as spam—and what you can do to prevent it.
Sending Emails From a Public Domain
If you’re sending emails from free domains like gmail.com, yahoo.com, or similar, mailbox providers are more likely to treat your messages as spam. These domains aren’t designed for bulk or business email sending.
How to fix it:
Send emails from a custom domain you own
Make sure the domain aligns with your brand identity
👉 Refer to: Dedicated Email Sending Domains Overview & Setup
DMARC Authentication Issues
If your sending domain has a DMARC policy in place but hasn’t been properly verified with your SMTP provider, your emails may fail authentication and be routed to spam.
How to fix it:
Confirm your domain is fully authenticated with your SMTP provider
Ensure your GrowthHub emails pass DMARC checks by following your provider’s setup instructions
List Quality & How You Collect Subscribers
Once technical setup is handled, list quality becomes one of the biggest drivers of deliverability. Poor list practices almost always lead to spam issues.
Make sure that:
Every Subscriber explicitly agreed to receive your emails
Inactive or unengaged Subscribers are removed on a regular basis
Signup forms use double opt-in for confirmation and security
For deeper insights, check out our Introduction to Email Deliverability guide.
Sending Emails Within the Same Domain
Are you emailing users on the same domain you’re sending from?
Example: sending from [email protected] to [email protected].
This often causes spam filtering because your mailbox sees an incoming message that appears to come from itself—but wasn’t actually sent internally (it was sent via GrowthHub). This can look like spoofing.
How to fix it:
For testing, send emails to external addresses like Gmail or Yahoo
For real internal communication, ask your domain administrator to whitelist your SMTP provider’s IP address
Sending Volume or Frequency Problems
Mailbox providers closely track how often you send emails and how many you send at once. Sudden spikes in volume can trigger spam filters.
How to fix it:
Gradually increase your sending volume over time (domain warm-up)
Keep your sending schedule steady and predictable
Avoid long breaks followed by large email blasts
Email Content Triggers Spam Filters
Even with proper authentication, your email content can still raise red flags.
Common content-related issues include:
Excessive promotional or urgent wording (e.g., “FREE $$$,” “Act Now,” “Last Chance”)
Emails made up mostly of images with little text
Use of link shorteners like bit.ly
Large attachments or unsupported file types
How to fix it:
Write emails in a natural, human tone
Maintain a healthy balance between images and text
Link directly to your website instead of using shortened URLs
Frequently Asked Questions
Q: How can I check if my emails might land in spam before sending?
You can use email testing tools that review content, authentication, and sender reputation. It’s also helpful to send test emails to different providers (Gmail, Yahoo, Outlook) to see where they appear.
Q: What should I do if my domain has a low sender reputation?
Start by reducing risk factors: clean your list, improve engagement, and slowly rebuild volume. Consistent sending and meaningful Subscriber interaction are key to restoring trust.
Q: How often should I clean my email list?
A good rule of thumb is every 6–12 months. Remove inactive Subscribers and those who haven’t engaged to keep your list healthy and protect deliverability.
Why Emails Get Marked as Spam (and How to Fix It)
Mailbox providers use many signals to decide whether an email belongs in the inbox or the spam folder. Below are the most common reasons emails are flagged as spam—and what you can do to prevent it.
Sending Emails From a Public Domain
If you’re sending emails from free domains like gmail.com, yahoo.com, or similar, mailbox providers are more likely to treat your messages as spam. These domains aren’t designed for bulk or business email sending.
How to fix it:
Send emails from a custom domain you own
Make sure the domain aligns with your brand identity
👉 Refer to: Dedicated Email Sending Domains Overview & Setup
DMARC Authentication Issues
If your sending domain has a DMARC policy in place but hasn’t been properly verified with your SMTP provider, your emails may fail authentication and be routed to spam.
How to fix it:
Confirm your domain is fully authenticated with your SMTP provider
Ensure your GrowthHub emails pass DMARC checks by following your provider’s setup instructions
List Quality & How You Collect Subscribers
Once technical setup is handled, list quality becomes one of the biggest drivers of deliverability. Poor list practices almost always lead to spam issues.
Make sure that:
Every Subscriber explicitly agreed to receive your emails
Inactive or unengaged Subscribers are removed on a regular basis
Signup forms use double opt-in for confirmation and security
For deeper insights, check out our Introduction to Email Deliverability guide.
Sending Emails Within the Same Domain
Are you emailing users on the same domain you’re sending from?
Example: sending from [email protected] to [email protected].
This often causes spam filtering because your mailbox sees an incoming message that appears to come from itself—but wasn’t actually sent internally (it was sent via GrowthHub). This can look like spoofing.
How to fix it:
For testing, send emails to external addresses like Gmail or Yahoo
For real internal communication, ask your domain administrator to whitelist your SMTP provider’s IP address
Sending Volume or Frequency Problems
Mailbox providers closely track how often you send emails and how many you send at once. Sudden spikes in volume can trigger spam filters.
How to fix it:
Gradually increase your sending volume over time (domain warm-up)
Keep your sending schedule steady and predictable
Avoid long breaks followed by large email blasts
Email Content Triggers Spam Filters
Even with proper authentication, your email content can still raise red flags.
Common content-related issues include:
Excessive promotional or urgent wording (e.g., “FREE $$$,” “Act Now,” “Last Chance”)
Emails made up mostly of images with little text
Use of link shorteners like bit.ly
Large attachments or unsupported file types
How to fix it:
Write emails in a natural, human tone
Maintain a healthy balance between images and text
Link directly to your website instead of using shortened URLs
Frequently Asked Questions
Q: How can I check if my emails might land in spam before sending?
You can use email testing tools that review content, authentication, and sender reputation. It’s also helpful to send test emails to different providers (Gmail, Yahoo, Outlook) to see where they appear.
Q: What should I do if my domain has a low sender reputation?
Start by reducing risk factors: clean your list, improve engagement, and slowly rebuild volume. Consistent sending and meaningful Subscriber interaction are key to restoring trust.
Q: How often should I clean my email list?
A good rule of thumb is every 6–12 months. Remove inactive Subscribers and those who haven’t engaged to keep your list healthy and protect deliverability.