The editor’s link checking (in templates and form captions, for example) now catches more undesirable or malformed links.

Background

When you include a link in a template or form caption etc, using Cameo’s tinymce editor, it checks it for validity. This applies to both:

  • text linked to other web pages, and
  • the source of an image

These checks include whether the link references a valid web page or image. However, previously Cameo only checked http(s) links: it ignored other kinds of link.

Link scheme checks

A link’s scheme is the ‘word’ before the first colon, the https in https://cameo-membership.uk/ for example. It tells the recipient what to do with the information after the colon. So https: tells them to open a web page.

There are many schemes, some more familiar than others. You may well have come across mailto:... for example. file:... says to open a file on the disk of your own computer when clicked. ftp:... says to download a file using the outdated FTP file transfer method. However, only https, http and mailto are really appropriate in emails and form captions.

Now, Cameo marks all other links as problems and explains why when you click them. Very often these arise when you copy from a web page, inadvertently bringing an inappropriate link with it.

mailto: links

Cameo now also checks that mailto: is followed by one or more valid email addresses. Though we let valid mailto links through at the moment, arguably you should not use them either.

That’s because they simply don’t work for many recipients, especially those who use webmail. They may disorient the recipient by opening a default mail app which is completely unfamiliar to them.

data: images

The data:... scheme for image sources needs a special mention.

Web pages use data:... to provide the actual image, encoded in the text that follows. (Contrast with https:... where the image is a reference to an image file on a server). Web pages sometimes use such images for small items like logos and icons (misguidedly, to avoid an extra round trip to the server to fetch it, at the cost of a larger page initially). If you copy the HTML for an image like that from a web page, you’ll take the entire image, not just a reference to it.

That causes problems for two reasons:

  • The editor attempts to spot and (incorrectly) convert such images into another scheme, blob:... (blob means binary large object). It is not easy to turn this behaviour off. Since both data:... and blob:... are inappropriate anyway, there isn’t much to be gained from trying to prevent this conversion.
  • A data image increases the size of emails significantly. When multiplied up by the number of emails sent it would put an undesirably high load on the Cameo’s server. The recipient would not welcome it either if they view it on a bandwidth-limited device such as a roaming phone. Spam checkers treat such images with suspicion: spammers can use them to hide text which would fail checks otherwise.

If you paste one of these by accident, instead capture the image and upload it to your website, and reference it there in the usual way.