Fixing Email Bounces: Guide For Returned Emails

What are email bounces?

Email bounces are emails that cannot be delivered and are returned to the sender. This can have various causes.

Types of bounces

Hard Bounce

A permanent error - the email can never be delivered:

• Email address doesn't exist
• Domain name doesn't exist
• Email server permanently refuses delivery

Action: Remove these addresses immediately from your list.

Soft Bounce

A temporary error - the email might be deliverable later:

• Mailbox is full
• Email server temporarily offline
• Message too large

Action: Try again later (automatically after 24-72 hours).

Common causes

1. Wrong email address

Typos in the email address (gmail.con instead of gmail.com).

Solution:

• Use email verification at signup
• Double opt-in for newsletters

2. Poor sender reputation

If you send too much spam or people mark you as spam, you get a bad reputation.

Solution:

• Only send email to people who signed up
• Make it easy to unsubscribe
• Avoid spam words in subject line

3. No SPF, DKIM or DMARC

Without these DNS records, email servers think your emails are spam.

Solution:

• Ask your hosting provider for SPF and DKIM records
• Add these to your DNS settings
• Test with Mail-Tester.com

4. Shared hosting IP on blacklist

On shared hosting you share an IP address with hundreds of other websites. If one sends spam, the entire IP gets blacklisted.

Solution:

• Use a dedicated IP for email
• Or use a professional email service (Google Workspace, Microsoft 365)
• Check our hosting comparison for providers with good email reputation

5. Attachments too large

Emails with attachments larger than 10MB are often refused.

Solution:

• Use file sharing services (WeTransfer, Dropbox)
• Send a link instead of the attachment

How to fix bounces?

Step 1: Identify the problem

Check your bounce messages:

• 550: Hard bounce (permanent)
• 552: Mailbox full (soft bounce)
• 553: Email address doesn't exist (hard bounce)

Step 2: Improve your DNS records

Log in to your DNS provider and add:

SPF record (example):

DKIM record: Get this from your hosting provider.

DMARC record:

Step 3: Test your email configuration

Send a test email to:

• Mail-Tester.com: Gives a score of 0-10
• Your own Gmail account: Check if it lands in spam

Goal: Score of at least 8/10.

Step 4: Clean up your email list

• Remove hard bounces immediately
• Remove addresses that soft bounced 3+ times
• Remove inactive subscribers (1+ year no open)

Prevent future bounces

Use professional email hosting

Shared hosting is often poor for email deliverability. Consider:

• Dedicated email hosting (Google Workspace, Microsoft 365)
• Transactional email services (SendGrid, Mailgun) for automated emails
• Hosting with good email reputation

Compare hosting providers on email features.

Monitor your deliverability

Check regularly:

• Bounce rate (should stay below 2%)
• Spam complaints (should stay below 0.1%)
• Sender reputation on SenderScore.org