A client of mine has installed contact form 7 for their contact forms but they're getting an error in the From field "(configuration error) Invalid mailbox syntax is used."

The form looks like this:

[text text-54 placeholder "Your Name"][text text-54 placeholder "Your Company"]
[email* email-317 placeholder "Email Address"][tel tel-646 placeholder "Phone Number"]
[textarea textarea-820 class:large-input placeholder "Tell us about your requirements"]
[submit "Request Callback"]

Now in the from field in the mail section they had

<[email your-email]>
so I changed it to
<[email* email-317]>

But I'm still getting the error? Thought that should have fixed it, can anybody spot anything else wrong with it?

3 Answers 3


The from field should be <[your-email]> - where you have specified it as a required field is only required for creating the field in the first place, not for transmitting the data in the mail section.

My general way for setting Contact Form 7 up is to use Website Name <[email protected]> in the from field, and then using the email submitted in the form in a Reply-To header instead.

Please refer to the Contact Form 7 documentation for more information.


Invalid mailbox syntax is used Error

You can find Invalid mailbox syntax is used error under the To, From, Subject or Additional Headers fields, that are located in the Mail Contact Form tab.

solve “Your contact form has a configuration issue” error

You have to solve this error. Otherwise, your email might not reach the addressee.

To cope with this error you might need to accomplish the next steps.

1] First, add valid email address to the To field (e. g., [email protected]).

2] Make sure that you use correct syntax in the From field (e. g., [your name] <[your-email]>).

3] Fill in your email subject to add information on your email (e.g., Site Name – [your-subject]).

4] You can add new fields to your contact form (e.g. phone number, city, etc.). Add the necessary content in the Additional Headers block (for instance, Phone: [phone]).

“This field can be empty depending on user input” Error

You can face This field can be empty depending on user input error if you’ve left Additional Headers or Subject fields empty. If you don’t want to use these fields, you may leave them empty, as they won’t influence sending messages. But if you face this error in To, From or Message fields, you’ll have Failed to send your message error when submitting a contact form. Fill in the fields correctly to avoid these kinds of errors.


Please check the screenshot and follow this link https://contactform7.com/configuration-validator-faq/. enter image description here

Not the answer you're looking for? Browse other questions tagged or ask your own question.