I don't think Firefox has a built-in email button. Do you have an add-on that created that button, or do you mean a button pinned to the Windows Taskbar?

If it's an add-on, check whether it has an settings available for window vs. tab. If this doesn't appear with the button itself (for example, using a drop-down triangle next to the button) you can check the Add-ons page. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Extensions. Then check the list for the relevant extension and try its Options... button.

You know you can customise Firefox, I added from the additional tools and features the email link to my toolbar (you know, the bar with searches and tools on the right). And each time i click on it, mail opens in a new window not new tab...

Oh, yes, the Email Link button. That is supposed to send your mail site instructions to compose a new message with a link to the current page.

That button should follow your setting here:

"3-bar" menu button (or Tools menu) > Options > Tabs > "Open new windows in a new tab instead"

If that is checked then you should get a new tab. If it not checked then you should get a new window. At least, that's how it is supposed to work.

Thanks!

that also means all other links open in new tab (which is good)