Why does the "max connection rate..." appear when using postfix?

Issue

• The following ourput :

Dec 28 08:59:53 hostA postfix/anvil[20017]: statistics: max connection rate 2/60s for (smtp:192.168.10.10) at Dec 28 08:59:46
Dec 28 08:59:53 hostA postfix/anvil[20017]: statistics: max connection count 2 for (smtp:192.168.10.10) at Dec 28 08:59:46
Dec 28 08:59:53 hostA postfix/anvil[20017]: statistics: max cache size 1 at Dec 28 08:59:43

• Why ?