EXPLANATION
What Is IMAP?
IMAP(Internet Message Access Protocol)
is the protocol used by the vast majority of consumer email accounts.
With IMAP, emails are stored on an Internet server. When a user accesses
their account, they’re connected to the external server, and data is
transferred from the server to their local machine – which itself
doesn’t actually receive any email messages.
One of the key
advantages of IMAP – aside from remote access – is that it allows a
single account to be operated and managed by multiple users, without the
need for a complex workaround. It can also put a fair amount of strain
on your mail server, if your business manages its own email service.
In order for IMAP to function, it requires one of two ports to be open:
- Port 143: The
default IMAP port; this allows the protocol to listen for incoming
requests to synchronize emails. Traffic through this port is
unencrypted.
- Port 993: Used for IMAP over SSL.
What Is POP3?
Unlike
IMAP, POP3 (Post Office Protocol 3) downloads messages from a mail
service to a user’s local computer. This allows the user to not only
receive emails on their own machine, but also to disconnect from the
Internet and retain access to all of their messages. There are a number
of advantages to this approach.
First and foremost, unless you’re
opting to leave a copy of each email on the mail server, it clears up a
significant amount of space by storing all files on the user’s local
machine. This makes it much easier to back up one’s email messages, in
addition to making search and organization far more efficient.
Unfortunately,
POP3 isn’t without its weaknesses either. The protocol by default
assumes that only a single user will be accessing a particular email
account, meaning that you’ll need a workaround if you want multiple
users on a single email. In addition, remote access can be something of a
problem. Finally, the fact that most POP services delete downloaded
emails from the server by default makes it incredibly difficult to
synchronize an account to multiple machines.
POP3 requires one of the following two ports to be open:
- Port 110: For unencrypted POP3 access; this is the default listening/communications port.
- Port 995: Used for encrypted POP3 connections.
Which One Should You Use?
And now for the million dollar question…which of the two protocols should
your business use?
The
short answer is IMAP. Given the wealth of different devices typically
used by modern employees, the capacity to remotely access one’s email
regardless of location is absolutely essential. The longer answer is
that – as always – it depends entirely on what you need email for.
The truth is, there’s really nothing stopping you from using multiple protocols to access an email account – the technology
does exist to do so, after all.
Sending Email: SMTP And HTTP
What Is SMTP?
Now, though there are two protocols
associated with receiving emails, there’s really only one associated
with sending them. SMTP(Simple Mail Transfer Protocol) is the gold
standard for passing email messages from one mail server to another.
Every email service uses some variation of this protocol.
There’s
one more difference between SMTP and IMAP/POP3: unlike the latter two,
it requires no authentication to function. Although modern SMTP
applications restrict relaying, this nevertheless allows for a fair
volume of spam to exist on the web; some tech-savvy criminals can even
send emails using another’s account.
There are two ports you’ll need to be aware of for SMTP:
- Port 25: This is the default SMTP port. It is not encrypted.
- Port 465 / 587: The default port for using SMTP through SSL.
In addition, some hosts may offer a secondary port as an alternative to clients for whom port 25 is filtered.
What Does HTTP Have To Do With Emails?
Now,
granted, I’m certain a few of you are at least a little surprised to
see HTTP (Hyper Text Transfer Protocol) included on this list. After
all, it’s not really involved in the process of sending or receiving an
email, nor does it directly interact with any of the other mail
protocols. So…what does it have to do with email, exactly?
Easy –
HTTP (and its more secure cousin, HTTPS) is the means by which you’re
probably going to access your mailbox, particularly if you’re using a
web-based email service like Hotmail or Gmail. For that reason, it
actually occupies a fairly important position in the grand scheme of
things, even if it’s not technically a mail protocol itself.