Avoid false spam decisions by Gmail's spam filters, stop losing critical emails in the spam folder
Gmail has done us all a great service by developing an excellent spam filter. I used to get hundreds of spam emails a day, and switching to Gmail reduced the spam rate to a few per week. No longer am I buried by spam. Of course the cost for this is to regularly visit the spam folder and see if Gmail accidentally marked any as spam (a.k.a. false positive for spam). Usually there's only a few and it's easy to click the "Not Spam" button to retrieve those emails back into the regular inbox.