What's wrong with my trigger?

I created this trigger:

BEGIN

DECLARE current_id bigint(20); DECLARE mail_address varchar(100); DECLARE user_id bigint(20);

SET current_id = post_id

SET mail_address = (SELECT meta_value FROM wp_postmeta WHERE post_id = current_id AND meta_key = "_from_email")

SET user_id = (SELECT ID FROM wp_users WHERE user_email = mail_address)

IF(exists( SELECT * FROM wp_posts WHERE ID = current_id AND post_type = "inbound" AND post_title IN ("Website feedback","General contact form")) THEN

UPDATE wp_posts SET author = user_id WHERE ID = current_id

END IF;

END;

but I get this error:

MySQL said: #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to user near 'SET mail_address... at line 9'

Do you spot any error in my syntax?

Any help is appreciated