Email protection: advanced settings

Hello Konrad Korneluk ,

Thank you for reaching out to the community, Max mails/connection:The maximum messages per SMTP connection requires a number in the range 1-65535.
Max connections/host:The maximum number of concurrent SMTP connections per host requires a number in the range 1-65535.
Note – If the value is 0 the connection number per host is unlimited.
Max rcpt/mail:The maximum number of SMTP recipients per mail requires a number in the range 1-65535.
Max connections:The maximum number of concurrent SMTP connections requires a number in the range 1-65535.
Max message size: The SMTP proxy maximum message size requires a number in the range 1-999.The maximum message size that is accepted by the proxy. This setting applies to both incoming and outgoing emails. If your backend server has a limitation with regard to message sizes, you should set the same or a lower value here. Default is 50 megabytes. The maximum message size limit is 250 megabytes. Unit is max connection per each mail you send.

Hello Konrad Korneluk ,

Thank you for reaching out to the community, Max mails/connection:The maximum messages per SMTP connection requires a number in the range 1-65535.
Max connections/host:The maximum number of concurrent SMTP connections per host requires a number in the range 1-65535.
Note – If the value is 0 the connection number per host is unlimited.
Max rcpt/mail:The maximum number of SMTP recipients per mail requires a number in the range 1-65535.
Max connections:The maximum number of concurrent SMTP connections requires a number in the range 1-65535.
Max message size: The SMTP proxy maximum message size requires a number in the range 1-999.The maximum message size that is accepted by the proxy. This setting applies to both incoming and outgoing emails. If your backend server has a limitation with regard to message sizes, you should set the same or a lower value here. Default is 50 megabytes. The maximum message size limit is 250 megabytes. Unit is max connection per each mail you send.

Thanks for the clarification.

I understand that it takes values 1-65535 per connection.

Why am I asking? In the logs, the server establishes a connection:

2023:06:09-10:14:11 mta03-1 exim-in[11486]: 2023-06-09 10:14:11 SMTP connection from [XX.XX.XX.XX]:49594 (TCP/IP connection count = 1)

this connection got the ephemeral port value - 49594.
In establishing the connection, the client system sent out thousands of emails. But at some point, I got lost connection:

2023:06:09-10:33:42 mta03-1 exim-in[22546]: 2023-06-09 10:33:42 rejected MAIL command H=(<srv_name>) [XX.XX.XX.XX]:49594: too many messages in one connection
2023:06:09-10:33:42 itcsr1mta03-1 exim-in[22546]: 2023-06-09 10:33:42 SMTP connection from (<srv_name>) [XX.XX.XX.XX]:49594 lost D=19m30s

From the log, I interpreted that after 19 minutes and 30 seconds, the server has saturated the Max mails value.

My server sends about 160k emails/flow unfortunately it is generated by the script.

From what I understand, my MTA will always disconnect the session because the server in this case will always saturate the limit of 65535 emails.

Your sending server's limit and capability highly depends !