Technical Help Centre - Gconnect - The Business ISP

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POP3 Mail collection POP stands for ‘Post Office Protocol’ and is probably the most common way of users receiving their inbound email. In essence, when a message for one of our customers arrives on the mail server, its is accepted and moved to a mailbox file which belongs to the customer. This process will continue with each message being added to the mailbox file. As well as a mail service (such as Sendmail) we also run a ‘Popper’ service, which allows the customers to access the mailbox file from their POP3 client such as Outlook (Express). When a user connects, the whole file is moved to a temporary ‘drop’ area and transferred to the customer’s local computer. When the process is complete, the temporary drop file is deleted, and the customer will be able to read the emails using the local POP3 client.   -   -   -   -   -   -

When setting up a hosting account, customers can elect to use POP3 as their collection method Advantages of using POP collection • Easy to configure • Less security considerations • Benefit from our anti-mail-abuse policies • ‘Always on’ connection is not required • Customers can utilise the ‘Procmail’ system • No special equipment or software required Disadvantages of using POP collection • Not real time mail • Quotas on mailboxes • No mail-store backup Sounds simple! But there are some important facts that are important in the smooth running of a mail system which uses POP. 1. Once mail is downloaded from the server it is deleted, there is no way of getting those messages back. Therefore it is not suitable for a mailbox accessed by multiple customers, or mail accounts accessed from different machines. Outlook has a workaround for this with the ‘Leave Messages on Server’ option, which itself can lead to quota problems (see below). 2. Mail boxes are limited in size, by default, each account is set to 40MB with and an extra 10MB for IMAP use.(see IMAP page for details). As each message is appended to the mailbox file, the system checks the quota level and if there is not sufficient space available, it will reject the mail back to the sender with an appropriate message. The reason we implement a quota system is that very large mailboxes can give customers problems when trying to download the data, causing corrupt mail files and effectively stopping the customers from seeing the mail, especially those on lower bandwidth connections. 3. POP3 is not a ‘real time’ mail system, you will only have email delivered when your client makes a request, for instance pressing the send and receive button, or using the client to schedule collection at regular intervals 4. Security is not a great problem with POP collection as the client machine does not need to run a service to collect the mail. Using a destination port of tcp 110 a connection is made from the user to our server and the data is returned, so the client can keep all vulnerable ports shut. 5. Gconnect’s anti abuse policies for which our mail servers are configured give POP3 collection users the benefit of a quite rigorous set of rules. Related Web Links to POP http://asg.web.cmu.edu/rfc/rfc1939.html RFC for POP3 standard http://www.eudora.com/products/unsupported/qpopper/ The POP daemon we use Mail Clients Supporting POP Just about all of them