Use SMEserver - Email Configuration
Your choice of e-mail retrieval mode will depend on the arrangements you made with your Internet service provider:
If you have a dedicated connection, set E-mail retrieval mode to "Standard".
If you arranged "ETRN" support with your ISP, choose that setting and then scroll down to the field that asks for the IP address or hostname of your ISP's secondary mail server. This secondary mail server will provide temporary e-mail storage when your server is not connected to the Internet.
If you arranged "multidrop" mail service from your ISP, choose "multidrop" and then scroll down to the field that asks for the IP address or hostname of your ISP's secondary mail server. This secondary mail server will receive all e-mail for your domain and store it in a single POP mailbox. Further down the screen, you will need to specify the user account and password assigned by your ISP for this POP mailbox. Your server will periodically fetch this mail and distribute it to individual POP mailboxes on the server. (Note that due to problems receiving mail for mailing lists, we strongly encourage people to NOT use multi-drop e-mail.)
If you want to forward e-mail to another mail server for processing, enter the mail server IP address in the box marked Delegate mail server . A common use for this is if your server is receiving inbound e-mail from the Internet, but you would like to pass that mail to a different mail server on your internal network. Note: Delegate mail server implies that all mail which is accepted is passed on to the delegate mail server (IOW, that other guy is the mail server, I'm not, so I expect him to do everything, eg spam filtering)
If you have a dialup connection, the server allows you to control how frequently it fetches e-mail from your ISP. This is particularly useful in situations where you incur phone or Internet charges each time your system contacts your ISP. The default settings are every 15 minutes during standard office hours and every hour outside normal office hours on weekdays or on weekends. The fields allow you to customize those settings.
Finally, if you have "multidrop" mail service you need to select the sort method used by the server to decide which user each message should be delivered to. Your server has a default method for this (it examines various headers such as "To" and "Resent-To") which works in most circumstances but is not suitable for certain purposes such as mailing list messages. Some ISPs add a header to each e-mail message which can help your server determine the correct recipient. If your ISP does not add a header to multidrop e-mail, select the "Default" sort method and ignore the "select sort header" field. If your ISP does add a header to multidrop e-mail, then select "Specify below" and enter the header tag provided by your ISP. Because you will experience problems with mailing-lists when using multi-drop e-mail, we strongly recommend that you work with your ISP to have a special header added to each message. The "Default" sort method should be only used as a last resort.