@everybody who is having problems with the update!
I think we all need to remember what a contact form is used for. It allows visitors to your website to send you a message – at no point should it be thought of as an alternative to email. (if you want the visitor to email you, then show them an email address they can use (yes, I know as soon as you publish an email address, you will start getting spam)).
Generally a contact form allows you to collect the Name, Email Address, Phone Number, Subject and Message from the person wishing to contact you.
In the past the collected data was saved to a text file, then for convenience it was sent via email to you, then to make it even more convenient it allowed you to set the senders email address as the From address — this was great as it allowed you to quickly send a reply, but it is now considered bad practice as a lot of spam (spoofed email) is sent like this.
In 2014 Yahoo, Hotmail, Gmail etc… all started using strict (DMARC) policies that rejected emails that were not sent from their own servers (e.g. you set your To email as [email protected] and the person using the contact form uses [email protected] — Yahoo knows it never sent the email from their server as it was sent by your contact form on your website, so Yahoo thinks it might be spam/spoofed and rejects it).
There are a number of way to prove the emails coming from your website are genuine, but the really simply way to resolve this, is to just set the From email address to be the same as the website domain name (e.g. https://www.mywebsite.com so use [email protected] <= you can add this to your email contacts so it isn’t wrongly marked as spam on your computer), then use the Repy-To: option in the Additional Headers field of CF7 so it uses the email address of the sender.
This way, you can still easily send an reply email to the sender — and you also avoid your emails looking like they are spam/spoofed if you use Yahoo, Gmail etc…
I know this is a long message – but the updates to CF7 are meant to help you run a better website.
I suggest reading the following to help understand how CF7 works and how to resolve validation issues.
Best Practice to Set Up Mail
https://contactform7.com/best-practice-to-set-up-mail/
How to Resolve Configuration Errors
https://contactform7.com/configuration-errors/
Contact Form 7 Configuration Validator
https://kb.cf7skins.com/contact-form-7-configuration-validator/