Maybe you would start thinking: why are you going to turn off a useful anti-spam feature? Well, we all know that Gmail's anti-spam filtering system is very powerful and useful. If I just don't want some important emails to be moved to junk, I can simply do a double check regularly. But what if I'm going to use another email account?
Of course I'll make the old Gmail forward everything into the new email. Like this:
However, in this case, Gmail would still filter the emails that it defines as junk and move it into 'spam' folder. And I'll have to check two email accounts to confirm that everything in the junk folder isn't needed.
Unfortunately Gmail doesn't provide the option in settings to turn off spam filtering. So we have to do this with an 'advanced feature': creating a filter.
First go to Gmail's settings, then Filters tab. Click on 'Create a new filter'.
In the 'Includes the words' textbox, type 'is:spam' inside (no quotation marks). Then click on 'Create filter with this search' button.
Gmail would prompt with a warning, which you can simply ignore. Click on 'OK'.
Select the 'Never send it to Spam' option, then click 'Create filter' button.
If everything was done correctly, you'll see a new filter created.
Now your Gmail would take every incoming email directly into the Inbox. And if you have the auto forwarding feature turned on, every incoming mail would be forwarded to your new email address, regardless whether Gmail thinks it's junk or not.