Best way to eliminate duplicate rows in a mysql table (Best Practice)

Question

Expensive,

I’m doing my first project on Mysql - I’m not an expert yet - so forgive me if the question is too easy.

I am migrating data to the Mysql database - it should have about 4-5 million records - and the table should not go beyond this because I will perform a periodic maintenance eliminating the "expired records".

Another maintenance to contain the number of records is to delete the DUPLICATE records.

for this I am performing the following script:

DELETE t1 FROM contacts t1
INNER JOIN contacts t2 
WHERE 
t1.id < t2.id AND 
t1.email = t2.email;

where CONTACTS is the table and email the reference field that cannot be duplicated.

I tested the script on a test basis (with 1000 records) and it works ok - however when executing it in the first shipment I made of the records - divided into batches with about 500.000 records - I’m already 15 Minutes waiting for the return (and the program just CRASH while I’m writing here.. rs - I am using HEIDSQL).

that is, when the base has 5 million - I believe it will be impossible to carry out this script.

So I would like to know whether there is another way - or a better practice for eliminating duplicates.

thanks for the help! daniel