I am infamous for having too many emails in my inbox. Over the years I would get frustrated and just signup for a new email account. Great. Let the old account pile up with nonsense and the new account can start to filter in.
Unfortunately, this is a disaster of an idea. Old accounts have passwords for services I do not check very often and having to link up which account had which service.
The purge:
The great email purge should begin one email account at a time. Starting with the oldest. Open it up and see whats going there. For me, it was a million and one newsletters and a ton of spam. But sifting through it, I found some fairly important accounts that were still linked to that email, because it was consistent. And 15 years later they were still together.
Purging each individual inbox, and then migrating whatever I still wanted to my current main email account reduces any security nightmares that may crop up, and lets me know that I never have to check that email again.
The daily grind
For me, inbox zero can be achieved by purging all emails at the end of the day by either answering them or adding them to my task management app ToDoist.
ToDoist has a great feature that lets you forward emails to your private ToDoist inbox, or to various projects that are tied to your account. This is handy for the end of the workday, forwarding in those emails to be sorted and assigned clears out my inbox, and clears out my brain.
For Replies:
I attempt to follow the three sentences rule in replying to emails as closely as possible, but often times end up with six sentences in an email response depending on the email.
I migrate any action points from the email into ToDoist and assign it to the correct individual or to myself and then delete the email.
Spending 15 minutes on this at the end of every workday helps tremendously with my ADD and gets my inbox down to the magic number of zero.