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             Can't Scroll a Message in Mail? Here's One Reason Why

   Adam Engst

   The report from J.C. Stauttener was unusual. He had received [1]the
   Dutch translation of TidBITS in email every week for years, but in the
   last few months, when he opened one, he wouldn't be able to scroll in
   the issue. His workaround was to reply to the message, at which point
   he could scroll through the quoted text with no problem. The problem
   started in macOS 10.15 Catalina, he said, but it persisted through a
   clean install of macOS 11 Big Sur. Nor did the problem afflict any
   other messages'just TidBITS in Dutch.

   I was, frankly, befuddled. None of my basic troubleshooting suggestions
   (testing in the preview pane versus a standalone window, trying a
   different user account or Mac, etc.) made any difference. While J.C.
   and I were going back and forth, our estimable Dutch translation team
   was investigating the problem as well. In short order, they figured it
   out.

   We frequently embed YouTube videos and Google Forms-based surveys in
   articles on our Web site. It's a superior user experience'rather than
   having to click a link and be sent off to YouTube or Google Forms, you
   can just watch the video or respond to the survey inline. However,
   email marketing company [2]Mailchimp recommends against including
   embedded video and content that uses the IFRAME tag in email messages
   because most email clients either don't support the necessary HTML tags
   or explicitly block them for security reasons (IFRAMEs often contain
   scripts that could be potentially malicious). As such, our custom
   WordPress-based system automatically strips embedded videos and IFRAMEs
   before sending an article in email or building an email issue. We
   always provide a backup text link for those receiving it in email.

   I had failed to mention this technical quirk to our translators, who
   have always created their own processes for translating articles and
   assembling them into an issue. Since they start their translation from
   the Web version of each article, they were getting the embedded videos
   and IFRAMEs in their source material. The Japanese translation team had
   independently discovered the problem and stripped any IFRAMEs from
   their issues, but the Dutch team, unaware of the concern, left them in.
   We use IFRAMEs only infrequently, but because we were running surveys
   alongside Jeff Porten's [3]CES 2021 articles, they popped up in quite a
   few issues so far this year.

   Therein lies the rub. Although Mailchimp says that Mail is the only
   major email client to support the HTML5 embedded media tags, it
   apparently cannot handle IFRAME content'or at least the IFRAMEs
   containing Google Forms that we were creating'or even fail gracefully.
   That's a bug, and I've reported it. I don't anticipate Apple devoting
   much attention to it, though, given how few people would accidentally
   include an IFRAME in email at this point in time.

   Nevertheless, if you ever find yourself unable to scroll a message in
   Mail, the reason is likely due to an embedded IFRAME in the source. The
   workaround is to reply to the message and read the quoted text, and you
   will gain tech karma points for alerting the sender to the problem with
   a link to this article.

References

   1. https://nl.tidbits.com/
   2. https://mailchimp.com/help/limitations-of-html-email/
   3. https://tidbits.com/series/ces-2021/

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