If you are having trouble sending emails, it's usually because of incorrect SMTP server settings, or a firewall/antivirus blocking access.
- Go to your Identity tab (Menu -> Settings -> Identities) then double click on the account that you are having issues with. After that click the test connection button and see what error message pops up.
- Try sending an email, with your firewall, antivirus, or proxy (if you are using this software) disabled.
- Make sure you use the correct server settings. For that just do a simple google search "Your email provider name + SMTP settings" and make sure you are using these suggested settings in the Identities tab.
If it still does not work, please contact support.