I cannot add a secondary email address.
I am trying to change my e-mail address by following the steps provided in here. According to the support pages, in order to do that I need to add a secondary e-mail address and then make it primary.
Until there everything's clear. My issue, though, comes precisely when I try to add that information. The system doesn't recognize the new address. Instead, a message appears saying "Account already exists", when that's not possible, since I never delivered it or linked it with Firefox before, nor even I have received or accepted any validation through the said e-mail. I'm guessing that Mozilla ain't grasping that the address really belongs to another e-mail client.
Illustration: Let's say my current address is <firstname.lastname@example.org> When I try to add the following secondary address <email@example.com>, the aforementioned message will prompt.
Why? What's going on? Is there any solution available? Thank you beforehand, I can't wait to hear from somebody with a remedy.