Form inquiries are not coming

hello,

we have been using Contact Form 7 plugin for more than a year already on our wordpress website.

several months ago we started receiving calls from our customers that the forms that they submit are not being acknowledged.

But we (as owner/admin) have never received their inquiries.

admin email is being used is a Google admin account with business domain. All plugins are updated and form is wet up accordingly.

please advise how to resolve this issue

thanks

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