We are currently researching why our campaigns are being sent from Sugar at a very slow pace. We recently upgrade our email server from Windows 2008 to Windows 2016 and ever since it seems like emails are processing one at a time from Sugar instead of sending in batches like it used to. We noticed that the process is Sugar will create a connection with our email server, send an email, disconnect, and then repeat. Shouldn't it create a connection, send all emails, and then close the connection? Has anyone experienced this behavior before?
We tested using gmail as the smtp server and the emails processed exponentially faster.
Here is a link to the errors we are seeing in the log files.
https://sugarclub.sugarcrm.com/explore/enterprise-professional/f/enterprise-professional-questions/3076/campaign-emails-very-slow-processing