It is common for Internet service providers (isp's) to block port 25 for sending e-mail. This is why we added port 26 as an alternative. Change your outgoing port of 25 to 26 via your outlook configuration to fix this issue.
Example Error Message:
Sending' reported error (0x80042109) : 'Outlook is unable to connect to your outgoing (SMTP) e-mail server.
Should you have any question/issues contact us through the client area and open a support ticket.