From the text of the license:

> If You distribute or communicate copies of the Original Work or a Derivative Work, You must make a reasonable effort under the circumstances to obtain the express assent of recipients to the terms of this License.

No wonder FSF criticise it and urges developers not to choose it! https://www.gnu.org/licenses/license-list.html#OSL:

> This means that distributing OSL software on ordinary FTP sites, sending patches to ordinary mailing lists, or storing the software in an ordinary version control system, is arguably a violation of the license and would subject you to possible termination of the license. Thus, the Open Software License makes it very difficult to develop software using the ordinary tools of free software development.