After OBAS was upgraded to 4.5.5 domains can not be provisioned to some of Plesk nodes with the following errors:
[2015/10/07 03:01:56] [INFO]  [HSPC::MT::Plesk::PleskGate::__send_request_to_agent] Failed to parse response::1: parser error : Extra content at the end of the document <script></script><p>ERROR: Call to undefined method Mail_Facade::setReject() [2015/10/07 03:01:56] [ERROR]  [HSPC::MT::BM::Subscription::PleskDomainSubscription::provision_domain_on_plesk] Cannot set(provision) settings of pdomain 'domain.tld' to Plesk: Could not connect to Plesk Agent host or response is empty.
The issue will be fixed in MU#69 for Plesk 12 and is already fixed in Plesk 12.5.
As a workaround, please replace the following files on the Plesk node(s) affected
C:\Program Files (x86)\Parallels\Plesk\admin\bin\plib\Service\Mail\Parameters.php C:\Program Files (x86)\Parallels\Plesk\admin\bin\plib\api-rpc\AbstractAgentMail.php
Workaround is applicable to Linux and Windows.