VPOP3 can receive email from your Internet provider using the SMTP protocol as well as (or instead of) the POP3 protocol.
SMTP has certain advantages, the greatest of which is that email addressing is explicit, rather than implicit as with the POP3 protocol, therefore there should be fewer message routing problems.
Different Internet Providers offer SMTP delivery to your server (VPOP3) in different ways:
The simplest is that your ISP automatically detects VPOP3 connecting and then starts sending the email within a few seconds without VPOP3 having to do anything special first.
Many ISPs use an extension to SMTP called ETRN, VPOP3 supports this popular method of triggering email collection.
Other ISPs require you to connect to their server first and issue a command to tell them to start sending mail. If this is necessary then you will need to create/install a Post-Connect Extension on the Misc page. This can connect to the ISP's server to send the command. Unfortunately ISPs use many different methods so this facility cannot really be built into VPOP3.
If you have a permanent connection to your ISP then you need do nothing special to VPOP3 to enable this facility.
If you have a dial-up connection to your ISP, and you want to use VPOP3’s connection or scheduling facilities, then you go to the In Mail Settings Page and choose the SMTP Incoming Option to get the following window.
In the SMTP (Incoming Mail) section you need to enter a time which VPOP3 should wait for an incoming SMTP connection over the dial-up connection.
This is necessary because usually the ISP’s mail servers takes a period of time to start sending mail, so VPOP3 needs to wait for this time before hanging up. VPOP3 cannot wait indefinitely for an incoming connection from the ISP because the ISP will not normally connect at all if there is no incoming mail.
If the ISP’s SMTP software connects to VPOP3 within the specified time, then VPOP3 will stay online until the connection from the ISP has finished (or until VPOP3 has finished sending mail, whichever is the longer).
Note: to use this facility you need to have IP Address to Bind To set to <Any> set for the SMTP Server on the Services Settings Page.
Some ISPs require will require an ETRN command to be sent to tell them to start sending your email to you (otherwise known as dequeuing your email). If this is the case, check the Use ETRN box, and enter your domain (or node) in the text box.
If you do this, then whenever VPOP3 dials any of the connections listed in the Use Connections list, it will connect to an SMTP server and send it an ETRN <domain> command which should tell it to start sending your email to you. Normally VPOP3 will send the ETRN command to the server specified on the OutMail page, but you can override that by entering the server to send the command to in the Send ETRN To Host: box.
If your ISP requires a different command to be sent to tell them to start sending you email, then you should obtain a program to send this command to them (ask your ISP if they have a suitable program) and run that program using the Post-Connect Extension.
When receiving mail using SMTP, VPOP3 uses the ‘Local Domains’ setting on the Local Mail Property Page to determine whether the incoming messages are for the local system, or need to be relayed back out again.