If you are using at least version 1.9.4, we have added a feature for email queue to speed up the email sending process.
Very common issue is when the system is sending a lot of emails, eq when a new comment on task, or task status is changed, the system will send an email to task creator, task followers, task assignees etc…
This action may be time-consuming when it’s related to email sending, the system will need time to connect to the email server and sends the emails, the time taken for this action really depends from email server to email server, some servers performs the action faster.
The email queue feature will store the emails and all contents in the database and when the cron job will run, the emails will be sent in the background, in this case, the users won’t notice any slowness.
To enable email queue feature you need to navigate to Setup->Settings->Email and click on the Email Queue tab and set Enable Email Queue to YES.
Do not add emails with attachments in the queue
Most likely you will encounter problems with the email queue if the system needs to add big files to the queue. If you plan to use this option consult with your server administrator/hosting provider to increase the max_allowed_packet and wait_timeout options in your server config, otherwise when this option is set to yes the system won’t add emails with attachments in the queue and will be sent immediately.
This is mostly applied to eq pdf documents or when sending some files manually, this process is straightforward, it’s recommended to leave this option to No if you are not sure what are you doing.