Mailto links have never really been an ideal way to collect responses to an email campaign.
However, it is unusual that our customers wanted to include a mailto link in their content. The problem is that major email providers outlook.com (previously Hotmail), Google and Yahoo might block your email if they detect mailo: Why? Not being able to see who you’re emailing does raise legitimate security concerns, thus the likely reason why companies block these links.
In addition to this, we’ve found that the Gmail app for iOS ignores any ?Subject or ?Body defined in mailto links. So much for that plan.
MailKing does support mailto: but it will try to replace mailto links with links to our website which will prompt users and ask them if they want to send messages.
Here are some alternatives to mailto links: