Been sending email from 2013 using xeams and have not experience any major problem since then, but we are experiencing "Could not send email after several retries" error for sometime now. Recipient are primarily yahoo mail accounts and secondary gmail mail accounts. We have no problem with our firewall appliance as the xeams mail server ports are properly opened and our domain is properly configured. Hope to hear from any one to solve this kind of problem as soon as possible.