Bulk mailing server configuration

My server sends newsletter emails on behalf of other domain not hosted on my server. Other server has set SPF and DKIM records and outgoing messages still gets into gmail's SPAM inbox. I need a mass mailing professional to fix this. I will not give root password so winning bidder will have to tell me what to do on my server. Cpanel of other server on where the other domain is hosted is availablre. Outogoing emails sent with my Joomla's Newsletter Component or phplist script must not be rejected due to wrong configurations. Communications and payment must be trough freelancer.com . My working time for communications is from 11 AM GMT to 9 PM GMT