Most people don’t stop to think what happens after they click “send” in their email program. Why should you? After all, the email’s on its way and all’s good with world right? Possibly. Possibly not. Read on to find out what really goes on, what can go wrong and, above all, why it really matters.
How does it work?
Whether you access your email on a PC, laptop, tablet or phone, the overall process of sending and receiving emails is the same and is modelled closely on the real-life process of sending a letter (remember doing that?). The process goes like this.
- The email is transferred from your device (PC, laptop, tablet, phone) to your email server (either your own physical email server at your company or one hosted externally).
- The email then gets transferred to the recipient’s email server (as above).
- The email gets transferred from the recipient’s email server to their device (PC, laptop, tablet, phone).
Compare this to the way posting a letter works…
- You put the letter in a post box and it goes to a local post office.
- The letter gets transferred to the recipient’s post office.
- The letter is delivered to the recipient’s address or the recipient picks it up from their local post office.
Pretty similar right? So far, so good.
Anyway, let’s have a closer look at those steps.
Step 1: Sender’s device to sender’s email server
Email is composed on the sender’s device using an email client or web page and is transmitted to their emails server in one of three main ways.
- On a corporate network, the company will probably run either Microsoft Exchange or Lotus Domino Server. The client software, Microsoft Outlook or Lotus Notes Client, sends the email to the server which can be either in-house or externally (“cloud”) hosted.
- If the sender uses a web page (eg. www.gmail.com), the message effectively gets sent to the appropriate server (eg. Gmail server) as a function of the web page and is transparent to the user.
- Most other times, the client device will send the message to the sender’s email server using the SMTP protocol (Simple Message Transfer Protocol). It is possible that messages sent using SMTP may be transmitted in plain text (ie. Could possibly be read somewhere along the delivery route).
Step 2: Sender’s email server to recipient’s email server (these could potentially be the same server!).
Before email can be sent, the sending server needs to know where to send it. Again, this part was modelled on a real-world system. See if you can see what it is.
- Sending server looks up the MX (Mail eXchanger) record(s) of the recipient’s domain. This tells the sending server the public name of the server to which to send the email.
A real MX record looks like this : upbeat.net.nz 20 mail exchanger = ASPMX2.GOOGLEMAIL.COM
- Sending server then does an “A” (Address) record lookup using the name it received above. This gives it the actual IP address to connect to.
A real “A” record looks like this : ASPMX2.GOOGLEMAIL.COM internet address = 188.8.131.52
- The sending server connects to the receiving server and, if successful, the email is sent.
The above process is much like using a telephone directory using a name to look up a telephone number.
Step 3: Recipient’s email server to recipient’s device.
As per Step 1, but in reverse except that messages are usually retrieved using POP3 (Post Office Protocol no.3) or IMAP (Internet Message Access Protocol). Proprietary systems, such as Microsoft Exchange, can “push” new emails directly to devices. POP3 and IMAP are very similar in that they both download messages from the user’s email server except that, in the case of POP3 they are deleted from the server after being downloaded* whereas IMAP keeps the user’s device (PC, laptop, smart phone etc.) “in sync” with the server so that the user sees an almost exact copy of what is on the email server at any time. With IMAP, emails deleted from the user’s device will be deleted from their email server and vice versa.
* Most email clients allow for emails to be kept for a short while after being “popped” from the server. Be aware, though, that storage space is usually very limited with POP3 mailboxes.
Microsoft Exchange works much in the same way as IMAP (at least as far as the user is concerned).
What can cause email delivery failures? (other than internet outages)
SPAM Filter at Recipient’s Email Server
Emails are checked as they arrive and, if they look “dodgy”, IE likely to be SPAM, then they are either deleted or, at least, put into a quarantine area. Sometimes, a non-delivery report is sent back to the original sender (which also may or may not make it!).
Blacklist Check by Recipient’s Email Server
The recipient’s server looks up the IP address of the sender’s server in a “blacklist” (a list of server addresses known to be involved in distributing SPAM) and, if it is found, the recipient’s server will block the attempted connection by the sender’s server. A non-delivery report may be generated and sent (and, possibly, lost in transit) as before.
Blacklist Check by the Sender’s Email Server
This time, the sender’s email server looks up the recipient’s email server address and, if it is found, will not send the email. If the sender is lucky, a non-delivery report may be sent back to say why the email was not sent. Sometimes, no non-delivery reports are generated, or they too get filtered out, so neither the sender nor the recipient knows that the email hasn’t got to where it is going thus a potential opportunity is lost!
The above scenarios all depend on the configuration of the individual email servers involved in the email exchange.
Why does this matter?
Email is an important business communication tool relied upon by businesses of all sizes all over the world so it makes sense that undelivered emails are a potential lost opportunity or even a source of potential conflict! A recent survey by “Return Path” determined that more than 20% of emails sent throughout the world go undelivered! That’s a lot of missed opportunities.
For smaller companies / individuals
Have your email hosted with Google, Microsoft or your domain host (Discount Domains etc.) as these will be less likely to be on a blacklist. ISPs (those that actually provide internet connections) often have a low reputation as their servers often appear on blacklists so should be avoided by business users for email hosting.
For Larger Companies
Make sure your IT team / provider checks blacklists regularly. There are many popular websites and tools which allow you to easily check your company IP addresses and make sure they don’t appear on any black lists. They also offer tools to allow removal from blacklists, should you be unfortunate enough to get on one, and to check the configuration of your email server. Send emails through a reputable relay provider to minimise the risk of being “black listed”. Companies such as Trend Micro provide (for a fee, of course) a service which, as well as scanning incoming emails for SPAM and viruses, also relays outgoing emails from your server increasing your chances of successful delivery.
UPBEAT Business Computing is an expert in email delivery and can assist with any problems you may be experiencing with this. Don’t let your business suffer because your emails aren’t getting to where they are supposed to!