What Is Causing This Error?
Error 450, ‘4.2.1’ is an SMTP response code from the recipient’s mail server indicating that the person you are trying to contact is receiving mail too quickly, and the peak limit of incoming messages has been exceeded.
This is a rate-limiting measure implemented by Gmail SMTP to maintain the quality of their service and prevent abuse.
Resolving the Error – Solution
To fix error 450, ‘4.2.1’, it’s best to wait before trying to resend your email, as the recipient’s server has hit its rate limit for incoming messages. For a better understanding of these limitations, refer to the Limits for sending & getting mail provided by Google. If urgent, use an alternative method to inform the recipient of the email delay.
That’s it! Now you know what’s causing the 450 limit exceeded error and how to resolve it.
If you’d like to learn how to troubleshoot other common errors, check out the following docs: