Yes, you can access your Ovi mailbox from mail.ovi.com as well as nokiamail.com.
As of 17 Sep, 2012, the mail.ovi.com domain was moved to nokiamail.com. It is still the same Nokia Mail service, now named Nokia Mail, powered by Yahoo! This was the final step in the process of re-branding Ovi Mail to Nokia Mail.
Now when you access mail.ovi.com, you are re-directed to https://www.nokiamail.com.
From now on, when you create a new Nokia Mail email account, the new user ID will be firstname.lastname@example.org. However, if you have registered an Ovi Mail account (email@example.com), your account will be unaffected. You can access your mailbox from either https://www.mail.ovi.com or at https://www.nokiamail.com.