Receive Connector Parameters for Ubuntu Postfix

Hello jonisthl,

no need to apologize, your language is not unprofessional.

1. By default, Postfix typically sends emails sequentially, one at a time, without establishing multiple connections simultaneously. However, if you have configured Postfix to use multiple outbound SMTP connections or if you have multiple instances of Postfix running, it is possible for multiple connections to be established. In such cases, the "MaxInboundConnectionPerSource" setting on the receive connector can limit the number of simultaneous connections from a single source (your Linux server).

2. The "MaxInboundConnectionPercentagePerSource" setting on the receive connector determines the maximum percentage of connections that can be allocated to a single source IP address. If your Linux server is the only system sending emails and it reaches the configured percentage (in this case, 100%), the receive connector may start rejecting new connections from that source.

Based on your description, it is possible that the current limits set on the receive connector are causing the issue. To address this, you have 2 options:

- Adjust the limits on the receive connector to allow for a higher number of simultaneous connections from your Linux server, considering the number of emails you need to send.
- Modify the Postfix configuration to limit the number of concurrent email deliveries or adjust the sending rate to ensure it stays within the limits set by the receive connector.

It's important to note that the specific configurations and steps to adjust these settings may vary depending on your environment and setup. Therefore, it is recommended to consult with your email server administrator or IT support team for guidance that is specific to your organization's infrastructure and requirements.

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Kindest regards

Leon Pavesic