rocknbil - 5:31 pm on Jan 23, 2012 (gmt 0)
If a user does not have a mail program registered on their system or never uses it (for example, someone who only uses a gmail account) a mailto link fails (e.g., there's no mail program for the browser to open, or the user may see it as an unexpected "pop up".) Form required.
If only takes a short amount of time for spammers to collect your email address from a mailto link on your site and bury your legitimate emails in junk. Form required.
Customers will email you with a problem and don't provide enough information to prompt a correct answer. Email forms guide them to asking the right questions. Form required.
Email itself requires a valid email address to send from. Many spammers submit emails just to get your email address. A form can be configured with a no-reply address from your domain as another layer of spam protection, and it makes no sense to configure your live email program with a no-reply address. Form required.
Actions by users in forms can be used to round out a statistical analysis of your site. Form required.
The "auto response" you send to clients when they submit a form can be used as another marketing piece to provide them information without having to create a template in your mail program.
Form required on business sites. :-)