In my Gmail account, an email from a sender went into the Spam folder, but I didn't want it to go there. It was the first mail received from this sender, which was not in my contacts.
I clicked on "Not Spam" and the mail was moved to inbox, then I answered to the email. Therefore the sender was automatically added to "Other contacts". Is this enough to prevent the emails from this sender from being sent again in spam folder (instead of inbox)?