When you are expecting an email from a sender, but did not see it in your Inbox, you may want to try searching it in the Junk folder instead. Sometimes, emails sent from a genuine sender could land in the Junk folder due to several reasons like sender's domain reputation, email subject matched your email rules, etc.
If you found the genuine email in your Junk folder, you can unjunk the mail, so that it is added into the server's “friend” list. This means that the next time this sender sends an email to you, the server will recognize the sender and allows the email to be delivered to your Inbox folder.
To unjunk an email, you can click on the Not Junk button. Once a mail is unjunked, it will be moved to your Inbox.
To avoid emails sent from known senders to land in Junk, we strongly recommend to add their email addresses to your Address Book.