Customer Should Receive Email Only Once

Hello Guys,
I really need you help to debug this query.
OBJECTIVE:THE QUERY SHOULD GIVE ME THE FIELDS I MENTIONED IN THE FIRST QUERY WITH THE CONDITIONS BELOW.
CONDITION 1: RateReview field should have yesterday's date
CONDITION 2: Email will be send to customer only once so Customer_GUID is UniqueIdentifier
CONDITION 3: Customer shouldnt' have opted to get out from receiving any email so Termination field should be NULL
ONe Customer can have many transwactions
Is there any way i write the code specifying that no email should be sent more than once evereven if customer buys 10 tickets.
Only one email sent so i need to specify that if this email has gone to particulare CUSTOMER_GUID then Ignore that record and
do not send any email. This would be done by some tool known as StrongMail.


SELECT
CAST(a.Transaction_GUID AS varchar(36)) as Transaction_GUID,
CAST(a.Customer_GUID AS varchar(36)) as Customer_GUID,
Film_id as MovieId,
First_nm as FirstName,
Last_nm as LastName,
Email_nm as EmailAddress,


from
(
select
MIN(CAST(customer_guid AS varchar(36))) as Customer_GUID,
Transaction_GUID
from tblTransaction (nolock)
where RateReview_dm > DATEADD(dd,-1,GETDATE()) and RateReview_dm <
GETDATE()


and Terminate_dm is null
and customer_guid
not
in
(
select CAST(customer_guid AS varchar(36)) as Customer_GUID
from tblTransaction (nolock)
where RateReview_dm > DATEADD(dd,-1,GETDATE()) and RateReview_dm <
GETDATE()

and Terminate_dm is null
)
group by transaction_guid, customer_guid
)z
inner
jointblTransaction a
onz.Transaction_GUID = a.Transaction_GUID