Mailto is a paid set of responsive HTML email templates by designer Vladimir Kudinov, built to render correctly across email clients and devices: sold both on UI8 and directly via getmailto.com.
Getting a marketing email to actually look right in Outlook, Gmail, and Apple Mail simultaneously is a genuinely fiddly, dated-HTML problem: a tested template skips days of client-specific bug-fixing.
Useful for a small team without a dedicated email-dev resource who needs a launch or marketing email that won't visibly break in half the recipients' inboxes.
It's a one-time paid purchase ($89), not a free resource: factor that in if you're comparing it against the free options in this category.
Email templates built to look right in every inbox, on every device.