Support - No-IP Support Center
Alternate-port SMTP FAQ 
Is there a limit to the number of recipients per email that I send?
Yes. In order to help protect against spam and mail flooding attacks, we limit the number of recipients per email to fifty (50). They can be either in the To:, CC:, or BCC: address lines, but there's a maximum of 50 allowed. If you need to send the same message to more than 50 addresses, you'll have to break the message up in groups of 50 in order to send it.
Don't forget that each recipient counts towards your total mail allowance, so sending one message to 50 people is the same as sending 50 individual messages for the purposes of metering usage.
Getting Started?
- We recommend you start with our Getting Started Guide which will walk you through all the basic steps to getting going with our service.
Still Need Help?
- Having trouble finding the answer you are looking for in our online support documents? First try our basic trouble shooting guide. If you still can't find the answer to your question feel free to open a Support Request or Contact Us.
Report Abuse
- If you believe a No-IP member's actions violate our Terms of Service, please inform us immediately at abuse@no-ip.com