Hello bbbbbb12,

Welcome to the Community. I'm here assist you with sending a mass email to customers.

Since we're unable received any reported issues from other users, let's perform some basic troubleshooting. Let's start with logging into your account using a private browser.

You can try sending a mass email again and check how it goes. If it works, you can switch back to your regular browser and clear the cache.

I've attached the shortcut keys below depending on the browser you're using:

• Google Chrome: press Ctrl + Shift + N  
• Mozilla Firefox: press Ctrl + Shift + P
• Internet Explorer: press Ctrl + Shift + P
• Safari: press Command + Shift + N

If the problem continues, let's try switching to a different supported browser. I need to check if the browser is causing the problem to happen on your end.

Please let me know how things go with the steps above. The Community has your back whenever you need further assistance.