Gmail's multiple account support distinguishes between Gmail accounts with just an index, which simply reflects the order in which you signed into Gmail:
https://mail.google.com/mail/u/0/
https://mail.google.com/mail/u/1/
…
So if you sign into Gmail first with test@example.com and then with notatest@gmail.com, https://mail.google.com/mail/u/0/ will go to the inbox of test@example.com; but if you sign into notatest@gmail.com before test@example.com, the same link will go to the inbox of notatest@gmail.com.
Aside from always signing into Google accounts in the same order, is there a good way to link to a specific Gmail account?
See also this related question on Google Groups.
Best Answer
Try the link below, changing the
test@example.comvalue as needed.