Do you mean when the domain expires from the registrar  ?

If so, yes that would be useful.  We have had clients where their domain expires for month or longer and we are holding their data and their domain is dead, or got purchased by someone else after it expired.

Yes we can fetch domain expiration date too, but if I am providing only mail services for existing domain and wish to set expiration date for mail services to a particular domain, so client shold know when his mail services are going to expire, after that date services to that paricular domain be suspended till renewed or activated by service provider. 

Are you using any type of control panel on the server ?  We use Plesk and it does that - subscription management.

I am not using any  panel, neither at this moment I require, Ijust want to have capaility to set date for expiry for renewal of services not the complete billing part