Open Outlook Express and select Tools. Click Accounts....
Click Add and choose Mail....
Type your Name (this will be shown when people receive a message from you).
Type the E-mail address, created in the control panel, and click Next.
Choose IMAP as your account type.
For incoming mail (IMAP), enter imap.one.com.
For SMTP server, enter send.one.com and click Next.
Type the e-mail address and password that you created in the control panel and click Next.
Click Finish to complete the setup.
Configuration of the SMTP server in Outlook Express
Follow these instructions to use One.com’s SMTP server.
Mark the mail account in the list and click Properties.
Select the Servers tab.
Check My server requires authentication if it is not already checked.
Select the Advanced tab.
In Outgoing server (SMTP) enter 465 and select This server requires a secure connection (SSL). In Incoming mail (IMAP) enter 993 and select SSL.