Troubleshooting Email Deliverability for Internal Campaigns

Troubleshooting: Not Receiving Your Own Campaigns or Test Emails

When you send emails from the application to yourself or others in your company, you may experience deliverability issues. The email might not arrive in the inbox at all, or it could bounce for all addresses using your company domain.


Why This Happens

While many factors influence deliverability, if you are failing to receive emails sent from someone@yourdomain to someone@yourdomain, it is likely that your own receiving mail server is blocking them.


Mail Server Blocks

  • External Server Rejection: Some mail servers are configured to automatically reject emails that arrive from an external server (like our application) but use the same domain in the "From" address that they host. The server sees an "internal" email address coming from an "external" source and flags it as a security risk.

  • Integrity Checks: The receiving mail server may perform additional security checks to verify the integrity of the email. This can result in delayed delivery or the email being blocked outright before it ever reaches your inbox.


How to Fix It

To resolve this and ensure your campaigns and tests are delivered reliably to your team, you should add our sending IP addresses to your inbox's "allow list". This tells your mail server that emails coming from our specific IP addresses are safe and authorized, even if they use your company’s domain.

IP Addresses to Add to Your 'Allow List'

  • 27.126.146.0/24

  • 103.28.42.0/24

  • 146.88.28.0/24

  • 203.55.21.0/24

  • 204.75.142.0/24


We recommend that mail administrators set up specific rules within your email filtering software. For the highest security and reliability, the rule should match both of these conditions:
  1. ​Originating Source: The email is coming from one of the IPs listed above or our sending domains (cmail1.com through cmail20.com, or createsend7.com).
  2. From Address: The email contains your specific company domain in the "From" address.
By configuring the rule this way, any email that does not meet both criteria can still be rejected, maintaining the security of your mail server while allowing your authorized campaigns to pass through.

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