I just got the dreamhost atmail account.
I can send email to my personal gmail using atmail dashboard but when i send back from gmail, i didn't receive email.
Please help for me.
There could be a number of factors when you did not receive an email back, from the information that you had provided I can only guess what the issue was. It sounded like it may have been a brand new account and with that potentially a new domain name along with it. It is possible that the issue could be that the Mail DNS records for the domain name did not propagate out yet to the dreamhost system. With new domains and new email accounts on the domain it can take up to 24 hours for the mail routing to resolve fully. There is information about DNS propagation here https://help.dreamhost.com/hc/en-us/articles/215840248-DNS-propagation-overview. Hope the issue was resolved for you!