Personally, I have about 10 Gmail accounts. That really isn't that much but, still, keeping track of all of them (and remembering to check in) really does get out of control. So, here's what I've done to simplify EVERYTHING so that I can control them all from ONE Gmail account.
- Create a Gmail catchall account. Name it anything you want but it's probably best if you include some reference to "catchall" or "total" or anything relevant to its purpose in the name (do not worry, the account name will never be used in replies.)
- Set Each Gmail Acct to Forward to the New Catchall. Simple enough. In each Gmail accounts settings, click the "Forwarding and POP/IMAP" tab and the first section allows you to set your forwarding details. It's up to you whether or not you want to leave a copy of the forwarded email in the original Gmail acct. Personally, I don't and I'll show you why in a second.
- Create a Filter & Label for Each Gmail Acct In Your Catchall Account. In your new catchall account, find the link that says "create filter" and, in "filter creation" mode, fill the "TO" section with the email address of one of your forwarding Gmail accounts. After clicking "NEXT STEP", you'll have the option of creating and assigning a "LABEL" to the forwarded emails you'll be filtering. In each case, you should probably name the filter something that would remind you of the place from which it came. So, if, for example, you are receiving an email forwarded from email@example.com, you'll probably want to assign the label abc123 to it.
- Create a Reply-to for Each Forwarded Acct In Your New Catchall Account. After you have all your gmail accts forwarding to your new catchall account -- and, after you have a filter set to label each incoming email forwarded to your new catchall, you'll want to create a "reply-to" for each gmail acct so that if you want to reply to any of the forwarded emails, you can do so with the "reply-to" address of the corresponding gmail account. So, when you reply to forwarded email firstname.lastname@example.org, you can reply AS IF you are writing FROM email@example.com even though you are writing from within the catchall account. This option is set by clicking the "Account" tab in Gmail settings and following the "reply-to" instructions.