Normally Smoke test will be conducted by Testing team 
before accepting a build for testing.

This build is internal to development company,not to client.

here one thing is very important to know, that is

Releases are two types:

1.Internal Release
2.External release

Internal release means for testing team
External release means for client or end user.

Normally for products before delivery company will conduct
two types of product based pre-release tests

They are 
1. Alpha Testing
2. Beeta Testing

Alpha testing is conducted by the inhouse people in end 
user perspective in a simulated real user environemnt.

Beta testing will be conducted by the end users in real
operational environment.

Real time example for this Beta-testing is:

Windows operating system - product of microsoft

Before releaseing to market company will release beeta 
version of the Windows O.S to users

The users are allowed to post comments on the beeta Windows 
O.S

If these comments are reasonable Microsoft will modify the 
O.S according to users comments.

User may give 
1.Suggestions to improve Product features to make more 
robust
2.User may find bugs in live testing enviornment
3.Usre may suggest some usability features..etc

So
Smoke test will be conduted for internal release and not 
for external release.

I think with my explanation u will be clear 

if u have still any doubt please contact me or mail me

byeee

Rajendra Prasad Reddy
rajendra_penumalli@yahoo.com
+919885162742
hyderabad
india

wen a build is received apart of test cases is run to 
ascertain, if the build is staable and it can be considered 
for further testing
1.somke testing is done for testing the stabilty of any 
interim build
2.executed for plateform qualification tests
3. Done on the initial stage

Sanity Testing is done at later stage , which is subset of 
regression testing

Yes, Smoke test will done before product release. Smoke 
test is done by testers, it ensures that product is not 
breaking before going to release and smoke test tests the 
basic functinality of entire application