Separate Security Issue, please update your Flash 28.0 r0 by removing it with this tool : https://helpx.adobe.com/flash-player/kb/uninstall-flash-player-mac-os.html If you use it Reinstall with Flash Player Version: 30.0.0.154 Current Version https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, . . . .) Note: Other software is offered in the download. <Windows Only>

As Firefox is a Browser and not a Email Client Firefox does nothing that your asking for.

Please see Help in the program or web site you are using. If looking for Help with Thunderbird please find it here : https://support.mozilla.org/en-US/products/thunderbird

Note that the OP is on an older Mac OSX 10.6 operating system and is likely not able to update to a more recent Flash version. The same for the Firefox 48.0.2 version although Firefox 45.9.0 ESR is more recent (released about 8 months later) and has more security fixes.

• https://download-origin.cdn.mozilla.net/pub/firefox/releases/45.9.0esr/mac/en-US/