Blocked Campaign: What It Means and How to Fix It

If your campaign shows a Blocked Campaign status, it means the campaign has been stopped from sending because a potential issue has been detected.

This is a safeguard designed to protect your sender reputation and improve deliverability.

In some cases, a campaign may be blocked while it is already sending. If this happens, some subscribers may have received the email while others did not. You may notice that the number of recipients sent to is lower than the total number of subscribers in the selected list.

Before resending the campaign, you'll need to identify and resolve the issue that caused the block.

Why Was My Campaign Blocked?

There are several reasons a campaign may be blocked.

High Spam Risk

Your email content may contain elements that are commonly flagged by spam filters, such as:

• Excessive use of capital letters
• Misleading subject lines
• Too many links or images
• Aggressive promotional language

What you can do:

• Review your subject line and email copy
• Remove unnecessary links
• Make sure your content accurately reflects the purpose of the email

Poor List Quality

Campaigns sent to outdated or low-quality contact lists are more likely to be blocked.

This can happen if your list contains:

• Invalid email addresses
• Large numbers of inactive subscribers
• Purchased or scraped contacts
• Contacts who did not explicitly subscribe

Understanding Bounce Types

Not all bounces mean an email address is invalid.

Some bounces occur because the recipient's mail server temporarily rejects the email. These are known as Soft Bounces and often resolve themselves.

Common examples include:

• Gmail rate limiting
• Microsoft / Outlook / Live rate limiting
• Mailbox full
• Temporary server issues
• Recipient mail server unavailable

Learn more about Gmail rate limiting

Hard Bounces indicate a permanent issue and usually mean the email address should be removed from your list.

• Examples include:
• Invalid email address
• Non-existent mailbox
• Domain does not exist

When cleaning your list, focus on contacts that have generated Hard Bounces.

What you can do:

• Remove invalid email addresses
• Regularly clean inactive contacts
• Send only to subscribers who have opted in

How to Remove Invalid Email Addresses

1. Open the CAMPAIGN.

2. In the BOUNCE RATE REPORT, click the three-dot menu. Select VIEW DETAILS.

3. EXPORT the bounce report.

5. Open the exported file and identify the contacts marked as Hard Bounce.

6. Remove any contacts marked as Soft Bounce, then save the file.

Once the file is ready:

1. Go to the mailing list used for the campaign.

2. Click MANAGE SUBSCRIBERS > VIEW SUBSCRIBERS.

4. Click ACTION > BULK ACTION.

This will remove the invalid email addresses from your list and help improve future campaign deliverability.

5. Upload the updated file. Under Action, select DELETE. Click SUBMIT.

Unusual Sending Activity

A sudden increase in sending volume may trigger a review.

For example, if you usually send to 1,000 contacts and then attempt to send to 100,000 contacts, the activity may be flagged automatically.

What you can do:

• Increase sending volume gradually.
• Segment large audiences into smaller groups.
• Warm up new sending domains before sending large campaigns.
• Use a Custom Defined Segment to create smaller, targeted audiences based on subscriber activity, engagement, or other criteria before sending. This helps reduce the risk associated with large-volume sends while improving campaign relevance.

For instructions on using the Custom Defined Segment

Domain Authentication Issues

Your sending domain must be properly authenticated before you can send campaigns.

Mail Blaze requires your domain to be verified using the correct DNS records. If these records are missing, removed, or changed, your domain may lose its verified status and campaigns may be blocked from sending.

The required authentication methods include:

• SPF
• DKIM
• DMARC

Missing or incorrect records can affect deliverability and may result in campaigns being blocked.

What you can do:

1. Log in to your Mail Blaze account.

2. Navigate to your PROFILE > VERIFIED DOMAINS.

3. Locate your sending domain. Check that the domain status shows Verified.

If the domain is not showing as Verified, your DNS records may have changed or been removed by your hosting provider or IT team. In this case, you'll need to review and update the authentication records before sending campaigns.

For detailed instructions, see Verify Your Domain

It's a good idea to check your domain status regularly, especially if you've recently changed website hosting, DNS providers, email services, or domain settings.

Resending Your Campaign

1. Once you've identified and resolved the issue that caused the block, wait at least 24 hours before resending the campaign.
2. This allows engagement data to update and helps ensure that subscribers who already received the campaign are not sent a duplicate email.
3. You can then use the Resend to Non-Openers feature to target subscribers who did not open the original email. For step-by-step instructions, see Resending Campaign

How to Avoid Future Campaign Blocks

To reduce the risk of future blocks:

• Build your list organically
• Clean your subscriber list regularly
• Authenticate your sending domain
• Monitor bounce and complaint rates
• Send relevant content to engaged subscribers
• Segment large audiences before sending
• Test campaigns before sending to your full list

Need Help?

If you've reviewed the steps above and your campaign is still blocked, please contact our support team. We'll be happy to investigate and help identify the cause.