What is SMTP Relay?

SMTP Relay Service is a gateway for sending emails, where the service provider takes care of almost everything leaving you with an ample amount of time to focus on your core product and business.

Before we begin, let’s read this detailed blog on Emails, protocols and other important terms.

A brief discussion on Email SMTP.

SMTP stands for Simple Mail Transfer Protocol.

SMTP is definitely one of the oldest and reliable protocols for sending emails. And, almost every programming language has a default function to support SMTP based MIME assembling and email sending. But, it has its PROS and CONS. The biggest advantage of SMTP is that it’s Universal which means you can switch from one platform to another platform easily just by changing the SMTP settings. No real coding or software changes. Now, let’s try to understand the challenges while dealing with Email SMTP for sending emails. Check out the flow of emails when you send it via the SMTP server through an email service provider, in the below diagram.


In-house SMTP Vs using a third party SMTP relay service

It’s definitely not a big task to set up an in-house Email SMTP relay server and write code to assemble the MIME header and send emails, but the major challenge comes;

  • when you want to scale- Here, the scale means sending more emails in the same time frame. On one hand, Email SMTP is an open protocol using which you can send an unlimited amount of emails but each mailbox providers like Gmail, Yahoo, Outlook who today dominates the entire mailbox industry has their own set of rules to accept emails over SMTP. So, sending more emails means hitting more such rules and thresholds.
  • Managing and blocking the spam complaints/unsubscribes
    The more the number of emails you will be sending, the more feedback loop integrations you have to do with the mailbox providers.
  • Analyzing the performance of your emails
    You should not be just sending emails, but you should be actually analyzing the performance of your emails, to know what is working and what’s not. The best way to analyze these is to track the email activities like Bounces, Opens, Clicks, Unsubscribes and Abuse complaints. Read on setting up bounce notifications.
  • Ensuring your emails are secure and comply with the latest standards, best practices, and trends in the email industry
    If you have not yet heard any of the terms like DKIM, SPF, DMARC, r-DNS, TLS then probably it’s time to stop and get these implemented.
    Also, TLS offers a great deal of email security.
  • Managing the reputation of your sender domain and IP address
    There are different global bodies who keep a track of your email sending practices and assigns a score to your domain and IP address. It’s important to analyze these scores and to keep yourself updated about it.

Most of the ISPs and mailbox providers like Gmail, Yahoo, Hotmail, etc, use these scores to decide whether to deliver an email or not.

Read this exclusive guide on Email Sender Reputation.

While there are open source libraries and tools which you can just install to get your Email SMTP server ready to send emails, but you will definitely agree that it’s not easy to manage all of the above. And, not to mention the cost of procuring servers and operations can’t be discounted.

This is exactly where you can decide to choose a good Third Party SMTP Relay Service, where you can just connect over SMTP ports like 25, 465 or 587 for your email delivery and rest assured about all of the above points.

Also, read this amazing article on the History of Electronic Mail by Tom Van Vleck.

When is SMTP Relay used?

SMTP Relay is used automatically. It does not require the involvement of the sender or the receiver. It is not used when the emails are to be sent within the same server. In cases where multiple servers are involved, SMTP Relay automatically comes into operation to speed up the process of sending emails beyond servers. Read our blog to dive deeper.

Also, WATCH this detailed video on sending emails via Email SMTP.

Pro Tip: You can also reduce SPAM with SMTP! Know more.

Tracking Emails sent via SMTP

When you send your emails with the help of an email service provider there is another layer of processes running through your email delivery process. It’s interesting that before Pepipost’s Email SMTP server sends your emails, our system tags it with link trackers in the body of your email. These pixels allow you to track and update you regarding emails open and clicked.

SMTP Integration

SMTP is the fastest way to get started with sending emails. Integrating Pepipost with your application is quite easy as it requires only the modifying of SMTP configuration.

You need to:

  • Change the SMTP username and the password to your Pepipost credentials.
  • Set the server hostname to smtp.pepipost.com.
  • You can connect via unencrypted or TLS on ports 25, 2525, and 587.
    In SMTP, one mail is sent at a time. All you have to do is connect your mailing server, or servers (if you have multiple) to Pepipost’s server.


Other helpful resources:

Confused about what to choose between SMTP and Email API?


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