Problem with replying to email sent from contact form

Hello,

I have a few sites, which use Jetpack contact form and Easy WP SMTP, all configured just the same way (one hosting, the same email application for all). They all work perfect, except one, where an annoying problem occurs since some time.

The problematic site works like this:
When a customer sends a message through the contact form, it lands in my inbox ([email protected]) under his name and email address – it is ok. But when I click on “reply”, the recepient email becomes my own address, so I send the reply to myself instead of answer my customer.

Of course I can change the address manually everytime when creating email, but this is not the solution I search for. All my other sites work good. I tried to find any difference in configuration between the sites, but with no success – the Easy WP SMTP plugin, as well as Jetpack, are set the same way.

Could you please help me locate the problem?

All the plugins are up to date, the same as the core.

I am not asking at plugin forums, because I am not sure what causes the problem – Jetpack / Easy WP SMTP or something deeper (did I mess something?). It is hard for me to tell when exactly did it start to happen, the site used to work perfect as all the other sites.
For sure it is not a problem with the inbox – it has no problem with all other emails, also it works with no errors in the other domains.

I just don’t know where to bite it.