@Sandeep Saxena - headers are set in /apps/console/commands/SendCampaignsCommand.php at line ~ 1253. You might comment line what you...
@miojamo - try this:
/usr/local/bin/php -q /home/send/public_html/apps/console/console.php send-transactional-emails --verbose=1
@tizaj - check this - https://forum.mailwizz.com/threads/gmail-spam-yahoo-is-fine.5608/#post-36249
@Yas King - you can upload some screenshots with this issue?
@tizaj - check this - https://forum.mailwizz.com/threads/general-error-2006-mysql-server-has-gone-away.3853/#post-24960
Separate names with a comma.