Error 451: This mail account has sent too many messages in a short amount of time.

SMTP Relay Account
The following instructions are provided for customers who have an SMTP Relay Account. If you do not have an account and would like more information, please contact our Sales Department.

Error Message
451 Requested action aborted: This mail account has sent too many messages in a short amount of time. Please try later.

Description
If you receive this error when attempting to send an eMail campaign, it means that you are sending messages faster than your SMTP Relay Service plan allows.
SMTP Relay Service plans have three items that define their limits:

1. How many recipients you are allowed to send messages to per month. 
2. How many recipients you are allowed to send messages to per hour.
3. How many sending domains you are allowed to use.

Resolution
To resolve this issue, you have two options:

1. Throttle your eMail software so that it sends messages slower. 
2. Upgrade your account to a service plan that meets your required sending levels.