I just got the dreamhost atmail/webmail account.
I can send email to my personal gmail using atmail dashboard but when i send back from gmail, i didn't receive email.
What cluster is your email on? To find out check the Data Center page in your DreamHost panel. If its sub3, there are issues with it. http://www.dreamhoststatus.com/2016/08/10/email-delays-on-homiemail-sub3/#more-18518