Mail with Payment Advice using Customize T code

Dear Expert,

We have made a customize report on which a Payment Advice is been send to the Vendor Mail ID. But the issue is that ones the Customize Tcode is executed the mail request is displaying in SOST tcode but it is not geting send in the Mail ID directly. We have to manually select and execute from there (Tcode SOST). My concern is ones the customize t code is been executed it will go to SOST tcode but it has to directly get sent to vendor Mail ID. We don't need any manual process again in SOST Tcode. What activity is need to be performed for that?

Please find the bellow attachment.

Its Urgent.

Please do the needful.