Reason
Your mail volume has reached the transaction limit, so our server has rejected the connection with a temporary error.
To ensure server performance, the transaction limit serves as a system protection against attacks that happen intentionally or because of a technical problem of the remote system.
According to RFC 5321 chapter 3.8. we are allowed to close the connection with a temporary error in this case.
Solution
If you receive a temporary error during a transaction, please close the connection, then reestablish it and start the affected transaction again.
Note that our current transaction limit is 100 transactions per SMTP session. You should expect that this value may change. No exceptions or individual limit changes will be made.
We recommend that you carefully plan the number of transactions per session to ensure that your sending practices comply with accepted policies. Once your system is adjusted accordingly, you should be able to deliver your emails to us without delays.
See also: General information on our error messages.