Delivery failure with “Messages queued (connection quotas met)” error

Last update: 2023-10-02


Campaign Classic

Getting the following error across multiple domains:

Deliveries failing with Error:

Messages queued (connection quotas met)


The quotas met message indicates that the email delivery is postponed by the MTA because a certain threshold has been reached while sending.

This threshold is set by the MX management rules under Administration > Campaign Management > Non-deliverables Management > Mail rule sets.

It is a safety measure to prevent IP blacklisting.

There’s a possibility that the thresholds are too low, but that’s a question for a deliverability expert to answer.

If the TLS parameter is not set, it will default to the value in the serverConf.xml file (enableTLS), which is false by default. Though the purpose of TLS is mainly confidentiality, it is possible that this parameter plays a role in deliverability. Connect with a support agent to get clarity.

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