Help!warning: Cannot Modify Header Information - Headers Already Sent By (output Started At……

[zlw8484]

hello，I have a trouble，
my site: 520see.com

everyone can post comment，but show：

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Warning: Cannot modify header information - headers already sent by (output started at /www/zxq.net/s/e/e/seeya/htdocs/wp-includes/class-phpmailer.php:489) in /www/zxq.net/s/e/e/seeya/htdocs/wp-comments-post.php on line 79

Warning: Cannot modify header information - headers already sent by (output started at /www/zxq.net/s/e/e/seeya/htdocs/wp-includes/class-phpmailer.php:489) in /www/zxq.net/s/e/e/seeya/htdocs/wp-comments-post.php on line 80

Warning: Cannot modify header information - headers already sent by (output started at /www/zxq.net/s/e/e/seeya/htdocs/wp-includes/class-phpmailer.php:489) in /www/zxq.net/s/e/e/seeya/htdocs/wp-comments-post.php on line 81

Warning: Cannot modify header information - headers already sent by (output started at /www/zxq.net/s/e/e/seeya/htdocs/wp-includes/class-phpmailer.php:489) in /www/zxq.net/s/e/e/seeya/htdocs/wp-includes/pluggable.php on line 850

I don't know why,and cannot fix it. not plugin and themes reason,sorry my bad english.

so plz help me to fix it,thanks!!