change mangment not reciving notifications in all phases

Hi Experts,

 

we are running HPSM 9.33 , we have an issue that in change managment if we rasie new change  and shift the phase to approval or implemantation or update no one recives an e-mail , it was working fine and suddenlly notifications are stoped.

 

in logs nothing shows about this topic, my quations where should i trublshoot and make sure evrything is fine for geting notifications ???

 

Note : for inractions and service cataloge we are getting the notifications.