One Gmail Account per 50 to 100 traffic sites.

A "Good Rule of Thumb" is to use 1 Gmail Account per 50 to 100 traffic sites.

Google limits the amounts of mail you can receive per minute, hour, and day. If those limits are exceeded, emails will start to bounce and some sites will automatically set you to "unverfied." Dave suggests up to 50 Traffic Sites with Super Solo Networks per gmail account, and up to 100 Traffic Sites without Super Solos Networks.  All Dave's 300+ safelists have Supersolos.

For Dave Mosher's sites, you can "turn off" email delivery by using MasterSafelistMails.  Simply select the site in MSM, and update with your userid and password. From that point on, all your credit mails and Solos will be delivered to MSM, so you will read your emails from MSM.

Dave suggests an alternative.  Download a free copy of Windows Live Mail 11. Then you can add your Gmail accounts, set to download from Gmail and delete from Gmail after download. Then set up a "folder" for each traffic site, and set "rules" so emails from a particular site go directly to that Site Folder. It will make things a whole lot easier for you to manage. Then you can click the folder of the site you need to click; click what you need; and then delete older emails.