Hello: What is the best way to get rid of invalid email addresses without deleting the lead?

There is a way to check the validity of email addresses before you add them to Marketo and you don't have to send an email using SMTP calls to the recipient's email server. If you have a lot of these, you can submit them to a paid service like StrikeIron and they will tell you which are invalid. If you only need to do a few occasionally, you can use a free service like one of the following. http://verify-email.org/ http://my-addr.com/free-email-verification-tool/verify-email-address/reverse-email-lookup/verify_email.php/ http://mailtester.com/testmail.php http://tools.email-checker.com/