Kā izrādās atslēgt spama aizsardzību pavisam google mailiem normālā veidā nevar.
Rezultāts ir tāds, ka šad un tad (bieži?) spamboxā iekrīt e-pasti, kas nav spams.

Ja nu nav nekādas vēlmes ikdienā pārbaudīt spamboxu tikai tāpēc, lai pārbaudītu vai tur nav iekritis kāds vajadzīgs mails, darām sekojoši:

Set up a filter.
- go to Settings --> Filters --> new
- type in the field "Doesn't have:" a large bit of junk text eg "qopqasdfsdfmsdfsdfiwuerfq"
- click on "Next step" (note - there is no warning with this method)
- select the "Never send it to Spam" option
- create the filter

Voila!  You can test it and note that all your existing emails will have passed.  
If for some absurd reason an incoming email DOES contain such a junk text string, then it will after all be truly really spam.