Every now and again our dedicated support staff gets the question about iframes and their compatibility with specific email engines. Sometimes it's about adding content from their own site, sometimes a social media like or share option. So we did some tests internally to get the information we needed to answer those questions properly.
We found after testing over a number of clients on multiple platforms (I believe we tested 24 over web, computer, and mobile), that the end result is that it's not a fantastic idea. Because iframes can conceivably link into malicious or questionable content, a lot of clients flat out won't touch them.
Here's a list of the clients that will display them at all, and which ones will just cut them right out. Just remember that this is true for your clients as well, so even if you switch clients, the customer's client may still be disabled. Educate your customers on which email clients they can use if they want to receive your iframes, but make sure that you educate them on the risks, too.
|Windows Live Hotmail||No|
|Apple Mail 3 / 4||Yes|
|Lotus Notes 6 / 7||No|
|Lotus Notes 8||Yes|
|Outlook Express 6||Yes|
|Outlook XP / 2003 / 2007 / 2010||No|
|iPhone / iPad||Yes|
|Windows Mobile 5||No|
|Windows Mobile 6||Yes|
|Android (default client)||Yes|
|Android (Gmail client)||No|
This means that most clients will not allow you to send iframes and block the messages before they ever reach their intended recipient. Because of that, it means that it's best if you find ways to link to the content you want to display to your customer, because if you include the content directly, less than half of the messages will be received.
Not at all, we have nothing against them, however, most of the systems your recipients use will bar those messages, marking them as spam straightaway because of the amount that this specific technology was used by spam-senders in the past. This is an unfortunate occurrence where the actions of a few ruined a good thing for everyone. SimplyCast doesn't prevent you from using an iframe in email projects, we just want you to be warned that they may not deliver properly.