Curious if any Marketo admins have experienced using FreshAddress and the plug-in capabilities there? Is sales able to fully function the connectivity? Easy-to-use? Automation process troublesome?
Any feedback would be great Looking to validate all current and future contacts automatically.
Email address validation checks are not 100% accurate and you risk blacklisting valid email addresses. If you can accept the risks, go for it.
N.B These do work better for B2C companies where your database mainly use free email services e.g. Gmail.com, Outlook.com, Yahoo.com etc...
You should explain why false negatives exist: because it's possible for a mailserver to block the SMTP connection from the verification service, while a connection from another source (including Marketo) might have different results.
In addition, a real-time verification callout is truly checking whether the address is emailable at that time which means transient problems with a mailserver/domain/mailbox will be surfaced as hard failures. (However, this doesn't mean they're wrong at that time.)