Too many smtp connections
when I run # tail -f /var/log/exim_mainlog
I see too many connection on the smtp from a specific IP (it's a customer of the server)
2025-02-24 16:12:04 SMTP connection from [178.147.187.110]:61636 (TCP/IP connection count = 4)
2025-02-24 16:12:04 SMTP connection from (RENA) [178.147.187.110]:61636 lost D=0s
2025-02-24 16:12:04 SMTP connection from [178.147.187.110]:61637 (TCP/IP connection count = 4)
2025-02-24 16:12:04 SMTP connection from (RENA) [178.147.187.110]:61637 lost D=0s
2025-02-24 16:12:04 SMTP connection from [178.147.187.110]:61638 (TCP/IP connection count = 4)
2025-02-24 16:12:05 SMTP connection from (RENA) [178.147.187.110]:61638 lost D=0s
2025-02-24 16:12:05 SMTP connection from [178.147.187.110]:61639 (TCP/IP connection count = 4)
2025-02-24 16:12:05 SMTP connection from (RENA) [178.147.187.110]:61639 lost D=0s
2025-02-24 16:12:05 SMTP connection from [178.147.187.110]:61640 (TCP/IP connection count = 4)
2025-02-24 16:12:05 SMTP connection from (RENA) [178.147.187.110]:61640 lost D=0s
2025-02-24 16:12:05 SMTP connection from [178.147.187.110]:61641 (TCP/IP connection count = 4)
2025-02-24 16:12:05 SMTP connection from (RENA) [178.147.187.110]:61641 lost D=0s
2025-02-24 16:12:05 SMTP connection from [178.147.187.110]:61642 (TCP/IP connection count = 4)
2025-02-24 16:12:05 SMTP connection from (RENA) [178.147.187.110]:61642 lost D=0s
2025-02-24 16:12:05 SMTP connection from [178.147.187.110]:61643 (TCP/IP connection count = 4)
2025-02-24 16:12:06 SMTP connection from (RENA) [178.147.187.110]:61643 lost D=0s
2025-02-24 16:12:06 SMTP connection from [178.147.187.110]:61644 (TCP/IP connection count = 4)
2025-02-24 16:12:06 SMTP connection from (RENA) [178.147.187.110]:61644 lost D=0s
2025-02-24 16:12:06 SMTP connection from [178.147.187.110]:61645 (TCP/IP connection count = 4)
2025-02-24 16:12:06 SMTP connection from (RENA) [178.147.187.110]:61645 lost D=0s
2025-02-24 16:12:06 SMTP connection from [178.147.187.110]:61646 (TCP/IP connection count = 4)
2025-02-24 16:12:06 SMTP connection from (RENA) [178.147.187.110]:61646 lost D=0s
2025-02-24 16:12:06 SMTP connection from [178.147.187.110]:61647 (TCP/IP connection count = 4)
2025-02-24 16:12:06 SMTP connection from (RENA) [178.147.187.110]:61647 lost D=0s
2025-02-24 16:12:06 SMTP connection from [178.147.187.110]:61648 (TCP/IP connection count = 4)
2025-02-24 16:12:07 SMTP connection from (RENA) [178.147.187.110]:61648 lost D=0s
2025-02-24 16:12:07 SMTP connection from [178.147.187.110]:61649 (TCP/IP connection count = 4)
What I don't understand is why is this happening? is this to check for incoming emails?
How can I limit this from server's side?
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Hey there! Yes, it seems like they have a device that may be misconfigured that is checking for emails too frequently.
If you know that is a customer's IP address you won't be able to block it. The best solution would be to have them check their devices to see what is causing the issue.
There isn't much you can do on the server besides limiting the number of SMTP connections, although that would affect all users on the system:
https://cpanel.net/blog/tips-and-tricks/setting-up-and-troubleshooting-smtp-in-cpanel/
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