Internal Mails not communicating in SAP

Dear All,

When we send mails to external Email Ids' like Gmail or Yahoo using the transaction SBWP, the recipient receives it, but when we send mails to internal SAP users, the recipient does not receive those mails. When checked in tcode SOST we see the error message "Cannot process message, no route from WF-BATCH to ED1:400:EXEIADSR" where are WF-BATCH and EXEIADSR is the sender and recipient respectively. The SCOT configuration is done using SMTP plug-in

Moreover this problem is coming in only one client and absolutely working in another client. Even tried comparing the settings, but happened to be of no help.

Please suggest as to how this problem could be solved. Its very urgent and I have tried everything i could think of.

Regards,

PP