After update version 7.7.9 error in campaign :
02/03/17 12:07:15 [1932][1][FATAL] Email delivery error:Array
(
[date_entered] => 2017-02-03 10:24:12
[date_modified] => 2017-02-03 11:07:01
[user_id] => 1
[id] => 32903
[campaign_id] => 9b350738-6824-deaf-233d-589459cf7ecf
[marketing_id] => 828d3775-d5f0-bbe7-38af-589459ae93d3
[list_id] => ee9bec69-7d14-be31-0e00-5886db148411
[send_date_time] => 2017-02-03 00:00:00
[modified_user_id] => 1
[in_queue] => 0
[in_queue_date] => 2017-02-03 10:39:50
[send_attempts] => 1
[deleted] => 0
[related_id] => eadd9aae-c2b0-4595-a105-58915e5d295d
[related_type] => Prospects
)
Could not execute: /usr/sbin/sendmail