How to limit TN delivery task threads by Partner or Processing Rule

Hello,

Is there a way to limit the maximum threads for the TN delivery tasks by Partner or Processing Rule?

We have two customized TN delivery servers, ZFTP and ZSOAP. The ZFTP is used to delivery the MATMAS data to one partner via FTP, and ZSOAP is used to delivery the ORDERS data to the other partner via SOAP, and there are a lot of messages need to delivery using ZFTP. And the problem we are suffering is the ZSOAP delivery tasks will stick for a long time when there are too much ZFTP tasks. This will cause the messages using ZSOAP much delay to delivery to our partners as the ZFTP tasks used up all the thread of TN delivery tasks threads.

So we want to find a to limit the max threads for the TN delivery tasks by Partner or Processing Rule, or we can set the priority of each document to insure the critical documents can be delivery first. Thanks in advance.

Create different queues in TN for ZFTP and ZSOAP so that delivery of documents will not interfere.