Generic email client configuration instructions

1. Just the facts
2. Explanation

Just the facts

Here are the things you minimally need to know to configure email client access to Mount Holyoke College's email system.

• On and off campus configuration:
• IMAP/IMAPS Server: mail.mtholyoke.edu
• POP/POPS Server: mail.mtholyoke.edu (prefer IMAP over POP!)
• Outgoing SMTP Server: smtp.mtholyoke.edu
• IMAP users should typically configure their IMAP server directory to be '~/mail' (sans quotes).
  (This can vary by client. Please refer to our specific configuration documentation to make sure you enter this correctly.)
• Off campus configuration:
• You must use secure IMAPS or POPS from off-campus. Unencrypted IMAP and POP are only available on campus.
• In your outgoing SMTP Server configuration setup:
• Use TLS
• Use password authentication, using your MHC username/password.

Explanation.

Basic server stuff

We have more than one type of email server on campus. An email server which stores incoming email for later retrieval by your email client is called an email hub. An email server that relays email between our campus and the outside world is called an email gateway. While these two functions could potentially reside on the same machine, for the purpose of distrubuting the work load, and to improve the reliability of email transmission in the event of a component failure, we seperate these functions onto separate machines.

IMAP and POP

IMAP and POP are both protocols that your email client can use to retrieve your incoming email. IMAP stands for Internet Message Access Protocol. POP stands for Post Office Protocol. There are number of differences between these two protocols, but for the purpose of this discussion, the most important distinction to make is that the POP protocol will move your incoming email off of the email hub onto your local computer; while the IMAP protocol will leave your email on the email hub, and manage it there. The advantage of using IMAP is that you can use multiple email clients to access your email. For example, you might use more than one computer to manage your email; perhaps one at home, and another at work. Because your email remains on the mail hub, both clients will see the same message store. By contrast, if you use POP at work, reading your mail would move messages from the mail hub to your local computer. Your email client at home would then be unable to see the same view of your inbox.

Both IMAP and POP come in secure and insecure versions. By secure, we mean that the connection between your email client and the email hub will be encrypted, making it impossible for anyone intercepting the transmission to view your email contents or see your password. Encrypting your connection is not as big a concern on campus as off campus, because our on campus LAN (Local Area Network) can for the most part be considered a trusted network. Virtually our entire campus LAN is switched, which makes it very difficult for people plugged into the same network gear as you to intercept your network traffic. We can make no such promises about a connection from off campus. For this reason, we do not even allow insecure IMAP or POP from off campus, you must use IMAPS or POPS.

As indicated above, the name of our email hub is mail.mtholyoke.edu. Use the same name whether you intend to use IMAP or POP. For historical reasons, other names may also work, but you should consider any other name deprecated, and migrate to the name mail.mtholyoke.edu.

When using IMAP, the mail server directory, which should be ~/mail, is where messages you move from your INBOX into other folders go. This may be (and on our system, is) on another filesystem than your incoming mail spool. Specifically, your incoming email is filed in a single file named /var/mail/<first_letter_of_username>/<username> , which is also referred to as your INBOX. If you use your email client to file messages from your INBOX into other folders, those folders will be created in a subdirectory of your home directory called 'mail', e.g. ~/mail/sent-mail or ~/mail/family, etc.

Outgoing email server

Your email client uses SMTP (Simple Mail Transfer Protocol) to send email, which is an altogether different protocol than it uses to read email (either IMAP or POP). Our email hub, which stores mail sent to you, has no role to play in the transmission of outgoing email (although your IMAP email client may also save a copy of mail you send using the IMAP protocol into your IMAP mail hub's server directory). Your email client communicates directly with our outgoing email gateway, which then relays your outgoing email to the incoming email gateways used by your recipients. As mentioned above, the name of our outgoing email gateway is smtp.mtholyoke.edu. For historical reasons, other names may also work, but you should consider any other name deprecated, and migrate to the name smtp.mtholyoke.edu.

We have traditionally required that you configure your off campus email client to use your ISP's SMTP server for outgoing email. Allowing unauthenticated use of our email gateway from off-campus would allow nefarious use our server to masquerade the origin of illicit or unsavory email, such as spam or virus attacks. This type of configuration even has a name: open relay, and is universally frowned upon.

As of August 24, 2005, you can use our gateway server to relay email from off campus if you configure your email client's outgoing email server to do password authentication using your MHC username/password credentials. This is called authenticated relay. If you do this, you should also configure your outgoing email server to use TLS, which is a protocol used to encrypt the SMTP transmission between your email client and the email server. When you send a message, you will be prompted to authenticate with your username and password (unless you have saved your password in your email client's SMTP setup dialog - a dubious practice). Once you successfully authenicate, our email gateway will accept your SMTP connection, and relay your mail to its destination.

Conclusion

The ubiquity of email, like HTTP and other protocols that define what we loosely describe as the 'internet', derives from the fact that is is built on open standards: primarily SMTP, IMAP, and POP. Because these are open standards, you can send and recieve email from others irrespective of your choice of computing platform. You can read our overview/ for more information about how we implement email services at Mount Holyoke College.