About Deletion Message in XI

Hi XI guru:

I have setup a deletion job in sxmb_adm->schedule delete jobs

it runs in every night.

now the question is : if I want the message which should be deleted are 30 days before, how can I set this parameter? which means the deletion job should obly delete messages which were generated at 30 days before.

I saw some posts said, it could be setup in sxmb_adm->integration engine configuration->specific configuration

but I don't know which exactly parameter is, please kindly let me know which is the one. thank you for your time.