Iframes are a great way to embed external content on your website, unfortunately they are not as universally accepted across email clients. Support for iframes varies across email clients, and unfortunately there is no easy way to display a fallback when an email client doesn't support iframes. This means your subscribers may or may not be missing out on some important content you wish to share.

In terms of email clients supporting iframes, only the following accept it:

• Apple Mail 3 / 4
• Lotus Notes 8
• Outlook 2000
• Outlook Express 6
• Thunderbird
• Windows Mail
• iPhone / iPad (Apple Mail for iOS)
• Android (default email client)

In conclusion, it may not be a good idea to embed iframes in to your email broadcasts. The best alternative is to copy the content over to the email, or take a screenshot and embed it as an image, then link to the page in the email.