Our filters rarely identify good mail as 'spam' but it can happen. For your own peace of mind you may want to whitelist your most critical email senders. When an email sender's address (or domain) is whitelisted their mail will never be marked as spam or be placed in the quarantine.
Here's how to whitelist a sender's email address or domain:
By default you'll be shown the Approved tab, which lists email addresses and domains that we should always accept mail from without filtering.
You'll be presented with a dialog box with a large text entry field where you can list the email addresses and domains that you want to whitelist.
Changes to your whitelisted sender list will normally take effect within 60 seconds.