Email protocols are standards that help transmit information by means of specific channels. They help in the establishment of a communication gateway between senders and recipients.
The significance of an email protocol lies in:
- Increasing the probability of the delivery of emails.
- Improving the reputation and reliability of the email sender.
- Enhancing the efficiency at which email services and software perform.
There are various kinds of email protocols – inbound, outbound, and bi-directional.
How Do Email Protocols Work?
The mailing process is initiated with the SMTP protocol that comes into play for transmitting outgoing messages. Furthermore, with the establishment of a TCP/IP connection, digital data is exchanged between MTAs or Mail Transfer Agents. These are intermediaries that function through synchronized ports. Eventually, emails are collected by receivers with the help of incoming protocols such as POP3 or IMAP via MDA or Mail Delivery Agent servers.
Even though the process is complicated, it is sufficient for you to understand the basics of the most commonly used email protocols. Below are some of the most popular email protocols:
- SMTP – To send emails
- POP3 and IMAP – To receive emails
- MS Exchange – To send and receive emails simultaneously
- HTTP – The universal protocol handling the World Wide Web, and used to both send and receive emails.
Basic Working Mechanism of Email Protocols
- Step 1: The sender enters the email address of the recipient, writes the main body of the email, and clicks on the “Send” option.
- Step 2: The email is relayed to a client-server by utilizing the SMTP protocol.
- Step 3: SMTP transfers the email directed to the client-server of the recipient.
- Step 4: The email lands in the inbox of the recipient, thanks to the inbound protocols POP3 and IMAP.
5 Best Email Protocols
1. SMTP (Simple Mail Transfer Protocol)
This protocol is simple and text-based. It shows maximum efficacy when devices have interconnection between them. However, the protocol is limited to only sending emails. It does not render the advantage of retrieving or downloading emails from the server when users wish to. SMTP use is restricted to a certain extent.
However, the SMTP server allows queuing of emails so that inbound messages could be delivered to the recipient. Also, SMTP does not support email authentication.
The SMTP protocol is used by UNIX systems or minor applications such as “mailsend”. SMTP does not find much use in widespread commercial applications.
By default, the three ports on which SMTP works are:
- Port 25 – It is the non-encrypted default SMTP port.
- Port 2525 – Every SiteGround server opens this port in case Port 25 is rejected.
- Port 465 – This port is utilized to work securely on SMTP.
Pros
- It requires no coding and is very easy to get going with the transaction of emails.
- It can work seamlessly with all types of devices.
- It performs overall synchronization of all email accounts with the help of its Smarthost server.
- It allows you to get statistical reports and analytics of transferred messages.
- In the case of any message not getting delivered, it sends an email back to you with an explanation for the failure.
Cons
- It is not very secure, which means that any email sent via SMTP can be easily hacked and users are more prone to receiving spam emails.
- It has server limitations due to which you need to adhere to the rules of proper hosting or follow the restrictions to connect to the internet.
- It requires more to and fro communication between servers for delivering messages which in turn can lead to a delay in sending emails or increase the possibilities of email bounces.
- A few ports frequently used with SMTP can be blocked by some firewalls.
2. POP3 (Post Office Protocol 3)
The POP3 protocol is a simple and standardized email protocol. It empowers users to access their mailboxes via the internet. Also, it enables users to download email attachments to their devices.
With its simple and effortless design, POP3 gives consent to users for getting access to emails. These are casual users with temporary internet connections. With the help of POP3, users can read emails, reply to emails, and draft new emails even when offline. They can send emails once the internet connection is restored. The server of Yahoo! Mail (mail.yahoo.com) makes use of the POP3 protocol.
The protocol allows clients such as MS Outlook to gain admittance to emails and get them downloaded from Yahoo! Mail. The emails are also accessible on common web browsers such as Internet Explorer (IE), Chrome, and Firefox.
By default, the two ports on which POP3 works are:
- Port 110 – It is the non-encrypted default POP3 port.
- Port 995 – This port is utilized to securely work on POP3.
Pros
- It is affordable as there are no requirements for any licenses.
- It is compatible with almost all devices.
- It calls for simple configuration and implementation.
- It keeps the availability of your mails intact even when devices are offline.
Cons
- It removes messages from the server after they are downloaded.
- It disallows the server to keep copies of messages after they are being sent.
- It allows emails to be downloaded based on the available bandwidth, meaning that it takes a while for big attachments to be downloaded.
- Even though it enables accessing mails on multiple devices such as desktops, smartphones, and tablets, still you may come across dissimilar emails on each device depending on the types of attachments that need to be downloaded.
- It does not permit any customization of the inbox, for instance, different inbox folders cannot be created.
- It has not had any major updates since 1988 and has become obsolete.
3. IMAP (Internet Message Access Protocol)
Users have recourse to this standard protocol for email transfer. As in POP3, IMAP also supports email access in both offline and online modes. Users can download email messages to their devices when certain requests are sent for reading those messages.
Even emails can be downloaded to individual computers, smartphones, or tablets while copies of them remain on the server. The server contains the primary email copies.
IMAP is known for its robust search capabilities. This helps users to look for emails more efficiently. This is helpful in the sense that emails are not required to be downloaded and thus, users can save time.
New mailboxes or folders can be created by users within the primary mailbox. Messages can be transferred back and forth between the primary mailbox and folders. This feature helps to access public or shared folders smoothly.
The Gmail server also uses IMAP. A client like MS Outlook may be helpful in directly accessing these emails. They can be obtained both on the IMAP server as well as the local device once the download is completed. Users can rely on popular web browsers such as IE and Chrome for reaching out to emails.
By default, the two ports on which IMAP works are:
- Port 143 – It is the non-encrypted default IMAP port.
- Port 993 – This port is utilized to securely work on IMAP.
Pros
- It does not need any license to be installed or renewed for its operation.
- It is compliant with all types of devices such as desktops, smartphones, and tablets.
- It supports timely synchronization of emails which lets users gain access to all messages.
- It has all its incoming and outgoing emails stored inside a server that is directly available and the emails do not need to be downloaded separately.
- It can organize an email inbox by adding multiple folders.
Cons
- It requires very powerful servers to function smoothly.
- If the IMAP protocol is not configured properly, the odds of folders getting duplicated becomes higher.
- It leads to the accumulation of emails in absence of any regular backup or the feature of deletion of old mails. It means that if you have a small storage capacity and you never delete emails, your inbox may run out of space.
4. Microsoft Exchange Protocol
It is Microsoft’s proprietary email transfer platform. It necessitates the purchase of server licenses. It offers functionalities that are identical to IMAP. Also, it helps businesses to effectively bring about a collaboration among team members and employees, especially for SMEs.
Pros
- It saves all incoming and outgoing mails in its servers.
- It carries out continual email synchronization, which makes sure copies of the same email exist both on the server and the devices.
- It can keep your inbox organized by allowing you to add numerous folders.
- It can be incorporated within Microsoft products like Office and SharePoint via native integration.
- It brings in unique collaborative tools, for example, file storage and shared calendars.
- The cost of its license can vary as it offers pricing plans on a per-server or per-user basis.
- It holds a mailbox whose capacity is much larger than those supported by POP3 or IMAP, which means that its “per GB cost” is quite competitive.
- It is regularly updated with new features.
Cons
- It is more expensive than POP3 or IMAP.
- It needs a license and servers for its operation whose costs can be exorbitant.
- Its setup and maintenance require more specialized knowledge and extra technical prowess.
5. HTTP (HyperText Transfer Protocol)
Note that the use of HTTP is not exclusively reserved for transferring emails. Nonetheless, it plays a crucial role in helping users who resort to their internet browsers for both sending and receiving emails.
HTTP is adopted by Yahoo and Hotmail to facilitate their users to access emails via the internet.
Port 80 is used by HTTP to establish a connection.
Pros
- It allows requests and/or responses to be pipelined.
- It reduces network congestion because of fewer TCP connections.
- It helps to report errors without cutting off the TCP connection.
- It gives rise to reduced latency in sending or receiving emails because of the absence of handshaking once the initial connection is established.
Cons
- It fails to offer any data reliability or integrity to its exchanges in absence of retry logic.
- It offers no data privacy and is at more risk of being intercepted by hackers.
- It does not have push capabilities.
- It is too complex and long-winded.
- It makes use of more system resources thereby resulting in more power consumption.
How to Choose the Most Appropriate Email Protocol?
It is worth noting that the application of an email protocol depends on your individual business needs.
- Select SMTP if there is a need to disseminate marketing campaigns and transactional emails to scores of customers. SMTP comes across as an all-important infrastructure component when it comes to sending successful transactional emails or newsletters.
- Select POP3 when email security is the overriding concern for your teams to collaborate. This entails the deletion of redundant copies of messages stored in unprotected servers. POP3 is also helpful in making you deal with a wobbly internet connection. POP3 is recognized as the perfect choice for individuals and small teams that do not want the intervention of others in accessing the mailbox. It is not ideal when you want to access the mailbox on multiple devices simultaneously.
- Select IMAP if you want to enjoy seamless accessibility in reaching your inbox anytime, anywhere. IMAP is ideal for teams that give precedence to flexibility and speed over a higher degree of security and server capacity. Opt for IMAP when you wish to have several tabs for sorting emails.
- Select MS Exchange when your team needs collaborative tools like calendars, shared contacts, file storage, and other Microsoft products. Companies that want absolute control of their email servers should opt for MS Exchange. Companies that have the technical dexterity to manage or maintain MS Exchange, either solely or by partnering with a reliable third-party, should go with this protocol.
- Even though HTTP is not designed to transfer emails, still you may select the protocol for exchanging messages to and from prominent web apps such as Gmail. Also, HTTP is known to be an excellent email access provider, especially for mobile apps.
Conclusion
Even though acquiring knowledge about the technical intricacies of each protocol can be tedious for business owners and marketers, there are many details combined with jargon that may be useful for you to get familiar with various email protocols.
To configure and implement email protocols you need technical skills and know-how. Ensure your team has sufficient development specialists on board to put relevant changes into effect.