The most important thing to know is your email must be “From” a valid address on your account. This means that you must use a contact form that doesn’t try to send using the email address of the person filling out the form as the “from” address. (That once was a common practice.)
For best results it’s been said the “to” address should also be on your dreamhost account. The problem with non-dreamhost “to” addresses is that some spam filters may see the originating mail IP as being a spammy origin.
Like kjodle said tho, you’re probably looking for a contact form plugin for your CMS.