Deleting the mimeTypes.rdf will reset all download actions to the default settings.

Type about:support in the address bar and press enter.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Locate the above file. Then rename or delete it. Restart Firefox.

When i by mistake click this line (Email Image...). Firefox will nonstop open tabs more than hundred tabs, then i should to close it and restart my PC. Please tell me what to do? Can i delete this line in this Window? because it is immediately after the line "Save Image As...". Please help me! Thank you.

Did you follow my instructions?

Hi Mr. FredMcD. Your instructions are not clear, so i don't know that file mimeTypes.rdf nor how could i reach to it. I have opened file browser and i didn't know what to do with it because your instructions are not step by step described so i left this and i have refreshed Firefox but nothing, the same problem still and sometimes freezing. Thanks my friend for your interesting. My best wishes

Those instructions are step by step. Just follow them. If you don't understand something, just ask.

Thank you for respond, please help me with the followings: 1- how can i delete that line " Email Image..." from the list. 2- make my Firefox browser fast. 3- or to prevent nonstop opening tabs. 4- where can i find that folder with name "mimeTypes.rdf" Thanks a lot my good friend, and tell me please are you a member of Mozilla Firefox or volunteer?

Read and follow the instructions I posted; https://support.mozilla.org/en-US/questions/1150479#answer-944032

Hi Hassan35yo, you might first try changing your preferred email setting on the Options page, Applications list, under "mailto." Whatever link it is using now seems to be causing this problem, so I suggest setting it to "Ask me" for the time being.

See: Change the program used to open email links

Hopefully that will work. If it doesn't work, then the mimeTypes.rdf file is corrupted and you'll have to delete it.

Actually, it says "Always ask" and not "Ask me" but probably you figured that out.