In the top menu bar click Mail.
Select the Preferences option.
Click the @ Accounts option in the top bar.
Click the Server Settings tab.
Edit the Incoming Host Name field to the following:
For POP3: pop.fusemail.net port 995 with TLS/SSL
For IMAP: imap.fusemail.net port 993 with SSL
Edit the Outcoming Host Name field to: smtp.fusemail.net port 587 with TLS/SSL
To edit the Incoming/Outgoing ports, UN-check Automatically manage connection settings. The Port field and Use TLS/SSL checkbox then appear.
Edit as needed. It's recommended to use incoming values of port 993 for IMAP and 995 for POP.
When finished, click the Save button.