How to know local IP on which mail was received on

Hello
So I have two IPs configured on my mail server (acting as MX for my domain).
Say public IPs are 1.2.3.4 (eth1) and 5.6.7.8 (eth2)
When I receive email, system logs sender IP but does not log on what IP the email was received on.
Log line looks like this:
Dec 11 08:26:48 foo1 sm-mta[1707322]: STARTTLS=server, relay=mail-ed1-f41.google.com [209.85.208.41], version=TLSv1.3, verify=NOT, cipher=TLS_AES_256_GCM_SHA384, bits=256/256
How do I know if email came on 1.2.3.4 (eth1) or 5.6.7.8 (eth2)?
I want to debug some issue which requires to know local IP the email came on.
Please do let me know, how to check the same.
Thank you,
AMM