How do I identify and raise number connections for Exim?

Introduction

How can I check how many connections are being made to Exim, and how can I adjust this if I need to?

Procedure

If you see service notification that Exim is going offline, but you're not seeing any other issues with email service, you may be seeing a connection limit occurring. To check this, grep for "TCP/IP connection count" against the Exim main log and look at the connection count. By default, this is 100.

grep "TCP/IP connection count" /var/log/exim_mainlog

2020-07-05 06:43:42 SMTP connection from [46.47.48.49]:23956 (TCP/IP connection count = 97)
2020-07-05 06:43:42 SMTP connection from [46.47.48.49]:53678 (TCP/IP connection count = 99)
2020-07-05 06:43:42 SMTP connection from [46.47.48.49]:46424 (TCP/IP connection count = 99)
2020-07-05 06:43:42 SMTP connection from [46.47.48.49]:45122 (TCP/IP connection count = 100)

To change this, navigate to Home » Service Configuration » Exim Configuration Manager » Advanced Editor Tab and look for smtp_accept_max.