July 5th was around the time that Firefox 22 was rolling out. That wasn't purely a security update, but did contain a range of changes, including some that were security-related. Nothing comes to mind as especially relevant to your problem.

Firefox has a glitch displaying some emails that, when examined, have a very deep nesting of HTML tags. That was the case in this thread: hotmail emails not displaying fully. While that problem is known, there isn't a convenient solution yet. The best workaround is what you've discovered: reply or forward displays the content.

Of course, the bigger concern is, you don't always know what you're missing, so hopefully this will be truly solved in a future version of Firefox.

The only reason I called it a "Security update" on July 5th was because the "history" section of Firefox referred to it as such.

So as to identify the problem more accurately, may I explain. In my email account I have several hundred emails from this vendor. They are simple price quotes on fuel. In the current Firefox version I can see every email perfectly up to and including July 2nd. But on July 8th and thereafter they cannot be seen. This leads me to believe that something changed in the format of the email that Firefox is not picking up. However, Explorer and Chrome does. I have asked the vendor what changes they made and they don't recall making any. When viewed in Chrome or Explorer I don't see anything different. Why the current version of Firefox can see the prior July 2nd emails and not the following July 2nd emails is perplexing to say the least.

Any clues?

My speculation would be that something changed in the underlying HTML of the messages themselves, and/or how they are rendered by your email site, that causes Firefox to view the July 3+ messages differently.

Do you see all text if you (temporarily) disable the CSS on that web page?

• View > Page Style > No Style

• Press the F10 key or tap the Alt key to bring up the hidden "Menu Bar" temporarily.