MYSQL INNER JOIN with Empty columns

Question

I'm trying to use MYSQL's INNER JOIN using two optional clauses. But it doesn't seem to be returning all the data. Any tips on how I can improve this query?

SELECT * 
FROM ImportedContacts t1 
INNER JOIN users t2 
    ON (t1.Emails = t2.email OR 
        t1.Phones = t2.Phone) 
WHERE t1.Username = 'user' AND 
  NOT t2.email = '' 
ORDER BY t2.first_name 
  LIMIT 60

EDITED

I changed the title from "MYSQL INNER JOIN with OR Clause" to the current one to make it easier to find for people having the same problem. It turns out this issue actually had to do with the columns being JOINED having empty or null values. The accepted answer explains the cause of the problem and provides a solution.

Answer 1

I found the solution. According to this article, INNER JOIN won't work with fields that have NULL or empty values. The Answer above didn't work since the CLAUSE that was meant to filter out the NULL columns ran after the INNER JOIN was evaluated with the NULL or empty columns. So considering this information I filtered out the NULL columns in the actual INNER JOIN statement as opposed to after.

SELECT * 
FROM   importedcontacts 
       INNER JOIN users 
               ON ( users.email = importedcontacts.emails 
                     OR ( ( importedcontacts.phones = users.phone ) 
                          AND NOT importedcontacts.phones = '' 
                          AND NOT users.phone = '' ) ) 
WHERE  importedcontacts.username = 'user' 
ORDER  BY users.first_name 

And it worked! thanks for the help guys.