I use Opera as a browser and I use Mail as the email client. In the preferences in the Mail program, there is a setting for Default Email Reader. When that is set to Mail, as I want it, the Share menu within other programs allows me to email from within the program, like from within Pages.
However, when the preference is set in Mail for Mail to be the Default Email Reader, after opening the Opera Browser, the preference in Mail is automatically (annoyingly) to be Opera as the Default Email Reader. The Share menu loses it's Email option, and I have to reset the preference in Mail.
My email address is gmail, and my wife has AOL. Our addresses are not associated with Opera; it's a problem with the software.