xp_sendmail- variable error

[ccp]

i'm trying to pass a variable into the @recipients of xp_sendmail. to start with, i have a stored procedure reading the values from a table and concatenating into a semicolon delimited string as follows:
/PROCEDURE [dbo].[p_auto_email_get_addresses]
/@email_group_id varchar(5),
/@email_addresses varchar(500) output
/AS
/declare
/ @email_string varchar(150),
/ @email_str_full varchar(500)
/
/set @email_str_full = ''
/
/declare crs_email cursor
/ for select email_address
/ from database.dbo.email_addresses
/ WHERE email_group_id like @email_group_id
/
/open crs_email
/
/fetch NEXT FROM crs_email INTO @email_string
/
/WHILE @@FETCH_STATUS = 0
/BEGIN
/ SELECT @email_str_full = @email_str_full+@email_string+ '; '
/ FETCH NEXT FROM crs_email INTO @email_string
/END
/
/SET @email_str_full = SUBSTRING(@email_str_full,1,DATALENGTH(@email_str_ full)-2)
/
/CLOSE crs_email
/DEALLOCATE crs_email
/
/SELECT char(39) + @email_str_full + char(39)

this returns something like 'jdoe@123.com; djoe@123.com'
i then pass this into xp_sendmail...

/declare
/ @email_to varchar(500)
/
/exec p_auto_email_get_addresses '%2%', @email_to output
/
/exec xp_sendmail @recipients = @email_to, etc, etc

I always get "Msg 17963, Level 16, State 1, Line 0
xp_sendmail: Procedure xp_sendmail expects parameter @recipients, which was not supplied." When i simply write in the value that @email_to returns then it works fine, so it's obviously an issue with the variable or the stored procedure. Any ideas or suggestions would be appreciated.

[mikr0s]

/*
Noticed, that in p_auto_email_get_addresses proc, there is no setting of the @email_addresses OUTPUT variable,
there should be a line like : SET @email_addresses = @email_str_full instead of SELECT char(39) + @email_str_full + char(39). Thus, output variable is always set to NULL, and when you are calling xp_sendmail, @recipients is always NULL

*/


CREATE PROCEDURE [dbo].[p_auto_email_get_addresses]
@email_group_id varchar(5),
@email_addresses varchar(500) output
AS

SELECT @email_addresses = ISNULL(@email_addresses , '') + ISNULL(email_address, '')+';'
FROM database.dbo.email_addresses
WHERE email_group_id LIKE @email_group_id

--Truncate last semicolon
SELECT @email_addresses = LEFT(@email_addresses , LEN(@email_addresses )-1)

--EOF--

DECLARE @email_to varchar(500)

EXEC p_auto_email_get_addresses @email_group_id = '%2%', @email_addresses = @email_to OUTPUT

IF LEN(@email_to) > 0
BEGIN
EXEC xp_sendmail @recipients = @email_to, etc, etc
END

--HTH--

[ccp]

that worked. many thanks.