Messages Stuck in adapter engine but passing through Integration engine

Hi All,

SOAPFault Error. Error Code/Category: XI Protocol/ Wrong Value...Received HTTP Response Code 500: Error during Parsing of SOAP Header

Above error as system error appears in adapter engine when messages are coming into SAP PI. At sender, we are having sender mail adapter.

Adapter Modules are also configured in mail adapter.What could be the possible reason.

Please suggest

Regards,

Kanisha