Email Alerts

I don't think you can do what you want. The only way would be to create a 2nd DL for the accounts you do want to use.

Not sure why you don't want to use the actual mail address, but each to their own I guess.

It is not possible as the DL members cannot be override from the SW perspective. However you can edit the alert and add only Y and Z as the alert recipients or you can create a second DL. 

Hi naresh_b,

The others are correct, this is not possible.  But in case you're looking to understand why it's not possible, here's the reason.

Speaking of internal distribution lists managed by an email server or directory system, such as Active Directory and MS Exchange: the distribution list is itself an email address.  When mail is sent to that address your exchange system will deliver the message to every member of the distribution list.  A sender from outside your organization would be able to send to the single email address assigned to the DL, and wouldn't be able to tell the difference between that address being a mailbox or a DL.  Internal members may (depending upon the mail client being used) be able to see the members (through something like a hover-over context box or expanding the DL).

In a case such as yours where you want to send to a subset of this DL the solution would be to create a new DL containing only the members you want (as either a DL that is itself a member of the existing DL which takes the place of the members in the existing DL, or as a separate DL).  I hope that last part makes sense. 

TL;DR: a distribution list is a function of your mail server or directory service, and has its own unique email address.  There's nothing that can be altered from within the address itself.