stucking messages in SMQ2

Hi Team,

I have a scenario ,Here we are using Bpms.Scenario as below.

Rec(Async)--->Send(Sync from CRM)--->Transformation(Merging response and actual input)--->Send(Asyn)placing as idoc in CRM.

Here i am getting invalid data in source file as Some X field 30-40 or 40+ like that..When i ever i get invalid data those messages are gtting stuck up in SMQ2.or else messages are processing successfully.

Here myy question is i need to raise an exception to avoid stuck up in SMQ2.Because if one invalid file gets stuck up all next messgeges are going in Queue.So i need to raise an exeption in mapping level or BPM level.

Please advice if we can achive through control step-->Exception handling,If yes how we can do.

Otherwise any otherway to acgieve?

Pls advice ...

Regards,

Narendra