MTA Queue

Hello,
My exhange server MTA have growing number of queue and couln’t send and receive emails. But locally we within our site se can send and receive.

I have dont the following and still we can’t send and receive it used to work before but nowit isnt working.

1. Run MTA check
2. Check Permission
3. Check service IMC and MTA stop and start service.
4. conduct rpc ping
5. Service account permission( i didn’t change any configuration).

Please help.

Thanks,,