CF7 in a Multisite

I have several domains in a multisite.
Since updating CF7 to Ver 5.6.1, I get a validation error for every domain in CF7 because the sender’s mail address is allegedly not from the current domain.
But the mail addresses are correct. If I enter the main domain of the multisite, the error disappears. But the recipient then sees a wrong sender mail.
Can I ignore the error and the mails still arrive or is there a solution to the problem?

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