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Email marketers rely on many different underlying architectures to deliver campaigns to subscribers. One of these architectures comes in the form of SMTP (Simple Mail Transfer Protocol).

SMTP works like HTTP (HyperText Transfer Protocol) by managing how mail servers communicate and transfer information over the internet.

What is an SMTP server?

An SMTP server is a mail server that handles outgoing messages from the source to the destination.

It does this with a set of instructions and syntaxes that route, queue, and transfer digital communications between different servers. The final step delivers the message to a POP (Post Office Protocol) or IMAP (Internet Message Access Protocol) server.

At this point, the message is available for the recipient to access. Once the message reaches its target, certain tools allow for gathering analytics directly from the servers.

Monitor your email metrics carefully to help spot deliverability issues more quickly.

Source: Campaign Monitor

How to measure the success of an SMTP server

SMTP usually comes as part of your service from an ESP, but you can configure your own, if required. The SMTP server manages all aspects of the communication and transfer, including authentication and queueing of messages.

Authentication is an important part of the process. This could influence whether a destination will accept the message and make it available to the recipient.

Seome ESPs require domain authentication before delivering the message. This means, by not setting up authentication, you could potentially see an increase in your bounce rates.

Bounce rates differ depending on your industry.

If you’re experiencing higher bounce rates than your industry’s average, consider checking your SMTP server’s authentication capabilities.

SMTP servers also have settings that determine how long a message should remain in the queue before coming back as undeliverable.

A Domain Name Service (DNS) that’s not available can delay the delivery of an email.

An overview of the SMTP transfer process starts when you hit the send button. Each email client connects to the SMTP server using a specific port, usually Port 25.

The client provides the SMTP server with the sender and recipient address, including the body of the message. The sender and recipient address provides both the user and domain information to the SMTP server.

If the recipient’s domain is different from the sender, the SMTP server communicates with that domain. By using a DNS, the sender’s SMTP gathers the IP address for the intended domain’s server.

The source SMTP then hands over the message to the destination SMTP server. The recipient’s SMTP will find the intended target and deliver the message to the POP or IMAP server. The recipient can now access the message from their email client, closing the loop.

Does it really matter?

SMTP is the only way to send emails over the internet. For digital marketers, choosing the right service provider will depend on a variety of factors.

The amount of emails allowed, the cost of the service per month, and the number of features included all have an impact on your campaign’s success.

Some service providers only support emails without the ability to send transactional emails.

Campaign Monitor’s service includes high-frequency marketing and transactional emails. The service also includes advanced analytics and insights for email campaigns.

With marketing automation, you can build rich and responsive marketing campaigns that increase subscriber engagement.

Campaign Monitor also supports domain keys to improve authentication and ensure higher deliverability of your campaigns.

What now?

SMTP is as vital to emails as HTTP is to the internet. Domain filters continuously update how SMTP servers handle communications from sources. Changes will influence which emails reach the intended recipients.

Now that you know how important SMTP is to your campaigns, why not read up on how to improve your engagement with subscribers for your next email design?

This blog provides general information and discussion about email marketing and related subjects. The content provided in this blog ("Content”), should not be construed as and is not intended to constitute financial, legal or tax advice. You should seek the advice of professionals prior to acting upon any information contained in the Content. All Content is provided strictly “as is” and we make no warranty or representation of any kind regarding the Content.
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