Email Service

CPTE 433John Beckett

The Fundamentals

• Reliable• Scalable

– Issue is speed• Flexible

– Clients, locations• Growing issue: Spam control• Growing issue: Storage

Privacy

• Fit with your organization’s culture.• Clearly state policy.• Distribute policy; get signatures.• Use policy as a statement of

maximum intrusion, not minimum.• Keep incidentally-acquired

knowledge secret.

Namespaces

• See previous chapter.• Two issues:

– Recognition of who this is– Non-duplication

• Special problem for colleges: marriage

• What about when people move around?– You might have an alias list pointing to

people with specific responsibilities, e.g. eclasshelp.

Reliability

• Upgrade plans for email must be laid more carefully than those for other services.

• Better to hold mail at bay than to lose it.– Simplest method: unplug the Ethernet

jack or take down the service

Aspects

• Mail Transport– This is done by the equipment designated to the

right of the “@”.– In DNS, this is the “MX” record.

• Delivery– GUI / non-GUI client– Webmail/OWA/SquirrelMail (is both client and

server)– Consider protocols used: POP3 and IMAP4

• List Processing– Big question is, who can send to which list?

Fading Technologies

• MTA on a client machine– May wish to deny this in your firewall

• Proprietary protocols – CCMail– CompuServe

Emerging Technologies

• Encryption*• Non-repudiation*• Spam control

* This is a reason SAU has migrated from Procmail to Microsoft Exchange Server.

Automation

• Setting up the account should be part of the process of signing up for a job.

• List administration should be automated either ex officio or at user’s election.

• What about when people leave? – No forwarding outside.– Either refuse the mail or send it to their

replacement.– At SAU: When does a person really

leave?

Monitoring

• Watch disk space consumption. That will tell you:– If someone is being attacked.– If you are not filtering SPAM properly.– If someone is using email to do something

that should be done through another process.

• Watch the bandwidth. – Positive trend: more bandwidth on

connection– Negative trend: SPAM

Redundancy

• Keep mail flowing in and out of the site even if one mail exchanger goes down.

Scaling

• Move other services off the mail machine.

• Separate mail functions such as WebMail client and MTA.

• Get a bigger machine.• Do a better job of SPAM control.• Provide alternate means or hosts for

troublesome emails – Art department example.

Security

• Your mail system will be a target.• If you count SPAM, it’s a target every

second of the day!• Watch the resources: disk I/O, disk

space, bandwidth.• Of course, stay updated.

Backups

• Do you want to back up local folders?– Yes: You have to be able to recover it if it

breaks.– Yes: You may be required to recover deleted

emails.– No: That’s not your job.– No: Leaves unnecessary records that could

be used by a prosecutorial opponent.• Backup policy should be clearly stated

and understood by all.

High-Volume Lists

• You may want to split the list into multiple sub-lists for simultaneous processing.

• GC example: From 4 hours to 30 minutes on a 30,000-person list.

Consider Off-Site

• Gmail.com is happy to do it (free!)