Effective December 1, 2016, ICANN is revising its Transfer Policy. Any change made to the registrant's name, organization, or email address will put the domain in a 60-day transfer lock; it will also trigger notification emails that are sent to the old and new registrant notifying them of the change.
Please visit the following article for further details:
The transfer process between DreamHost accounts is very similar to transferring a domain from an external provider. First, the account holder that is releasing the domain must prepare the domain for transfer in their own panel, by following the steps in the Transfer your domain registration away from DreamHost article.
Some international domains cannot be transferred from account to account using this process. In these cases, the receiving customer’s panel requests that they contact DreamHost support for further assistance.