Email service providers maintain their own whitelists and blacklists of domains and senders. If a service detects a large number of spam emails coming from one particular domain, then the host will shunt emails from that domain directly to spam from then on. Alternately, providers maintain whitelists for trusted domains which will always appear in a user’s inbox, whether the email is solicited or not. For the major providers, there is no way to request placement on these lists – inclusion is based solely on a domain’s reputation.
How to Whitelist Emails in Spam Folder of your mailbox?
If you find an important email in your spam folder that is not spam always take a moment to mark it as “not spam” or “not junk”, this automatically lets your email program add the sender to the whitelist.
If you are still not able to whitelist our email then, Click here to see domain-specific steps.