Dreamhost will never give info to a 3rd party. "I've been recently hired by my company" makes it hard to figure out your relationship to that company. I suspect you mean you've been hired as a contractor. You would be better to have someone with the company make contact with dreamhost using an email address that dreamhost can make the association. If you have a 3rd party email address that can't be associated with the account at all dreamhost will neither confirm nor deny the account exists, in short that means no reply to you.
If no one has any idea who created the dreamhost account you might try public WHOIS for the domain in question. If that doesn't lead you in the right direction, then have someone with an email address within the domain make contact and ask how to recover the account. Dreamhost does have a procedure, just be aware it's not quick, they must be very careful to not compromise the account.
By the way, why would you delete the mailboxes and set them back up again if they are the same?