I use Gmail (Even my a...@bkpark.com is actually a Gmail account, through the free (well, set up when it was free and then grandfathered in) Google Apps), and my recent complaint has been that its spam filter got really aggressive—as if the people working on Gmail’s spam filter didn’t realize that false positive is a deadly thing in a spam filter. I would tolerate 100 false negatives (i.e. spam that gets through the filter) before I accept a single false positive in a spam filter.
This didn’t used to be a big problem; I check my spam folder occasionally, and all the other email accounts I have (mostly from various systems at UC Berkeley) that forward to my main account at a...@bkpark.com didn’t have such an aggressive spam filter. It became a problem when I migrated my CalMail account to bMail, Google-hosted email for UC Berkeley.
I realized this when a student claimed—even against (unfair) accusation of lying—that he sent an email that I never received. When I finally thought to check the spam folder on my abkp...@berkeley.edu account, there I found his email, along with a couple other emails from students and 100 or so actual spam. This was an untenable situation; I was never going to check this spam folder, because I never check my abkp...@berkeley.edu account; that’s why I had my mail forwarded. I couldn’t tolerate a single false positive—and when I thought about it, this must’ve been responsible for one incident last semester when the instructor said he emailed me a draft of the final for my comments that I never received.
Apparently Gmail spam filter cannot be deactivated. You can, however, put in filter rules that effectively de-activates the spam filter. When you create a filter (under Settings; you might have done this to automatically apply labels, etc.), there is a checkmark for “Never send it to Spam”. So all you have to do is create a rule that is virtually guaranteed to match all incoming email, and check the option never to send it to Spam.
There are a couple ways to do this: One is to match for the at-sign (@) in the “To” field; the other is to match for a word that you are sure that legitimate email would never have in the “Doesn’t have” field (I personaly use عَرَبِي/عَرَبِى).
Once you set up such a rule, you will find a nice (for me, anyway) side effect—apparently the filter rules apply to outgoing emails, and what Gmail means by “Never send it to Spam” is “Always send it to Inbox”—you will find your outgoing emails in your inbox, in addition to the “Sent” folder. For someone like me, who compulsively labels all email (in fact, my email backup system is set up to back up only email that’s been labeled), this is a nice side effect—it reminds me to label the sent email before archiving them.
P.S. It goes without saying, but this is a kludge—and it may not continue to work in the future (hopefully in that future, Google gave us an option to turn off the spam filter …).