I recently experienced a strange problem. I tried sending an email to another user on our domain. He never received the email in his inbox. Instead it got sent to his junk mail folder. I found it by logging onto mailboxes.mydomain.com. We have also noticed that sending emails to other users on our domain can sometimes take longer to receive than messages that come from outside our domain.
I have whitelisted @mydomain.com in the junkmail settings. Is there anything else I can do to prevent this issue from re-occurring?