Concerning the viewing of embedded images on iPhones, after a lot of research and looking to see what other companies have experienced, it seems there are two predominant methods for embedding images, the CID (content-ID), and the straight filename method. What happens is that when an email sees an <IMG> tag, it finds the SRC parameter and examines it. If it is a normal URL with HTTP, it will assume a referenced image and load it in from a server. If the SRC does not have an HTTP beginning it will assume it is an embedded image and look for the reference in the SRC in the related sections in the message and attempt to load the image from that reference block. The other method in the SRC parameter is the “CID” method which is one of the first standards for loading content into HTML messages that are hidden. Problem is that Apple iOS devices only support the CID method but some other email clients and Webmail clients may ignore or will format CID referenced files strangely. There is no way for the email itself to detect the mail client and adjust things, that would be nice but then that would be scripting which is not allowed in emails. So, with what I have read, experienced in the past, and am experiencing now it seems like there is no universal solution to this, even for the big boys. Most opt not to use embedded images because of size and SPAM issues so I don’t think much thought is given to the technology anymore or somehow making it universal. As of Campaign Enterprise version 12.0.257 we will be using the CID method since it seems to more accepted by most email clients and mobile devices.
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