switfmailer 邮件时间错误 处理

Warning: date(): It is not safe to rely on the system's timezone
settings. You are *required* to use the date.timezone setting or the
date_default_timezone_set() function. In case you used any of those
methods and you are still getting this warning, you most likely
misspelled the timezone identifier. We selected the timezone 'UTC' for
now, but please set date.timezone to select your timezone 
in /home/jaydeepkanada/public_html/ramienterprise.com/swiftmailerTest/swiftmailer-5.x/
lib/classes/Swift/Mime/Headers/DateHeader.php on line 119