You need to contact the support for your email service, they are the ones who set the limits for your email.

Firefox is a web browser and not a email client. Even then whether you are doing it in one of the huge number of webmails in Firefox or in say Thunderbird, it looks to be a problem with the email service you are using as they usually have restrictions on various things.

'''Other issues that need your attention''' The information submitted with your question indicates that you have out of date plugins with known security and stability issues that should be updated. To see the plugins submitted with your question, click "More system details..." to the right of your original question post. You can also see your plugins from the Firefox menu, Tools > Add-ons > Plugins. *Adobe Shockwave for Director Netscape plug-in, version 11.5 *Adobe PDF Plug-In For Firefox and Netscape "9.4.1" **New Adobe Reader X (version 10) with Protected Mode was released 2010-11-19 **See: http://www.securityweek.com/adobe-releases-acrobat-reader-x-protected-mode *Next Generation Java Plug-in 1.6.0_20 for Mozilla browsers #'''Check your plugin versions''': http://www.mozilla.com/en-US/plugincheck/ #*'''Note: plugin check page does not have information on all plugin versions''' #'''Update Shockwave for Director''' #*NOTE: this is not the same as Shockwave Flash; this installs the Shockwave Player. #*Use Firefox to download and SAVE the installer to your hard drive from the link in the article below (Desktop is a good place so you can find it). #*When the download is complete, exit Firefox (File > Exit) #*locate and double-click in the installer you just downloaded, let the install complete. #*Restart Firefox and check your plugins again. #*'''<u>Download link and more information</u>''': http://support.mozilla.com/en-US/kb/Using+the+Shockwave+plugin+with+Firefox #'''Update Adobe Reader (PDF plugin):''' #*From within your existing Adobe Reader ('''<u>if you have it already installed</u>'''): #**Open the Adobe Reader program from your Programs list #**Click Help > Check for Updates #**Follow the prompts for updating #**If this method works for you, skip the "Download complete installer" section below and proceed to "After the installation" below #*Download complete installer ('''if you do <u>NOT</u> have Adobe Reader installed'''): #**Use the links below to avoid getting the troublesome "getplus" Adobe Download Manager and other "extras" you may not want #**Use Firefox to download and SAVE the installer to your hard drive from the appropriate link below #**Click "Save to File"; save to your Desktop (so you can find it) #**After download completes, close Firefox #**Click the installer you just downloaded and allow the install to continue #***Note: Vista and Win7 users may need to right-click the installer and choose "Run as Administrator" #**'''<u>Download link</u>''': ftp://ftp.adobe.com/pub/adobe/reader/ #***Choose your OS #***Choose the latest #.x version (example 9.x, for version 9) #***Choose the highest number version listed #****NOTE: 10.x is the new Adobe Reader X (Windows and Mac only as of this posting) #***Choose your language #***Download the file, SAVE it to your hard drive, when complete, close Firefox, click on the installer you just downloaded and let it install. #***Windows: choose the .exe file; Mac: choose the .dmg file #*Using either of the links below will force you to install the "getPlus" Adobe Download Manager. Also be sure to uncheck the McAfee Scanner if you do not want the link forcibly installed on your desktop #**''<u>Also see Download link</u>''': http://get.adobe.com/reader/otherversions/ #**Also see: https://support.mozilla.com/en-US/kb/Using+the+Adobe+Reader+plugin+with+Firefox (do not use the link on this page for downloading; you may get the troublesome "getplus" Adobe Download Manager (Adobe DLM) and other "extras") #*After the installation, start Firefox and check your version again. #'''Update the [[Java]] plugin''' to the latest version. #*Download site: http://www.oracle.com/technetwork/java/javase/downloads/index.html (Java Platform: Download JRE) #*Also see "Manual Update" in this article to update from the Java Control Panel in Windows Control Panel: http://support.mozilla.com/en-US/kb/Using+the+Java+plugin+with+Firefox#Updates #* Removing old versions (if needed): http://www.java.com/en/download/faq/remove_olderversions.xml #* Remove multiple Java Console extensions (if needed): http://kb.mozillazine.org #*Java Test: http://www.java.com/en/download/help/testvm.xml