Email clients consider email forms to be a security risk. While some email clients simply warn you of potential danger, others outright disable the forms. So if your client wants to send out a form, they should know that most of their recipients will never be able to use it. And for those who can, they'll think twice about submitting data when they see a warning from their email client.

We recommend linking to a form on a website rather than embedding it in the email. This is the safest, most reliable solution to pairing an email message with a form. More people will see it and be able to use it. As a result, participation will increase.