11 Best Scalable SMTP Relay Service to use in 2020
Written by
Jasmine Handa

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11 Best Scalable SMTP Relay Service to use in 2020

Published : May 24, 2020

While Email marketing has now become the need of the hour, getting the right tool that will help you meet the marketing objectives is equally important, and so a remarkable SMTP Relay service is that cog in the wheel that will help your business to achieve the best ROI through Emails. So, here we are to help you with 11 best scalable SMTP relay service to use in 2020.

But first, you might want to know, how necessary it is to get the right and scalable SMTP relay service for your business!

Why do you need a Scalable SMTP Relay Service?

As your business grows, outsourcing an SMTP relay server will help you to fulfill the growing need of sending emails to a large email list of your subscribers. You need such an SMTP relay service that will help you to scale up to millions of emails so that as and when required, you can send any amount of emails without compromising on the fact that they might land into the spam folder.

You already know that mailbox providers have super protective custom filtration algorithms which are so strong that even the legitimate emails of yours can land to spam folders. So, avoid that from happening and send your emails with the help of a powerful SMTP relay service so that you get an equally powerful email campaign.

11 Best Scalable SMTP Relay Service to use in 2020

Most of the email services use SMTP to send the bulk of emails. Here are a few that are doing great in the marketing landscape. 

1. Pepipost

Now, to start with, the very first in our list is Pepipost! You can send the bulk of emails using Pepipost by merely configuring SMTP in your applications, and there you go, your emails will start landing in the customer’s inbox folder. You can also perform email marketing with Pepipost integration with open source email marketing tools. It offers the best pricing plans in the email industry and the round the clock customer support to resolve your queries. No one can beat Pepipost on that! If you do not trust us, why don’t you check the reviews on the best review sites like TrustPilot, G2, Capterra, etc. We will definitely be on the same page then!


  • You get a real-time analytical report and webhook details so that you know the health of your email program.
  • Pepipost authorizes you to make sub-accounts & provide its access to them according to the roles.
  • You can buy Dedicated IPs at a very affordable price so that you get the best reputation and deliverability.
  • SPF, DKIM, DMARC-All the security measures are taken care of so that your email is securely sent to the recipient.

And the feature list goes on….

2. Moosend

Moosend provides its users with a super easy and quick way to email marketing and building beautiful emails. You can manage various email campaigns easily with the help of this SMTP relay service/tool. It offers multiple features like advanced automation workflow builder, with built-in automation templates etc. It is a perfect platform for bulk email transactions and messaging.


  • The tool comes with a powerful real-time analytics. 
  • Provides integration with CRM, app directory, CSM, e-commerce, list validation etc.
  • Drag and drop editor through which you can create and design amazing transactional emails and newsletters.
  • This email marketing tool has a spam testing assistant, which uses real spam filters and checks the HTML content and helps you detect spam email.

3. Sendgrid

Next, we have, SendGrid! Although we do not need to talk much about them, as they are very renowned in the email marketing spectrum. It is an exclusive SMTP provider that offers its extraordinary services for bulk emailing. You can send both marketing and transactional email through their Web API or SMTP API to more deeply integrate into your system.


  • You can easily integrate and deliver with their SMTP relay service. 
  • They provide open-source libraries in 7 languages, and a clear set up to help you send emails right away.
  • You can access Email templates with HTML rendering and conditional formatting with testing previews.
  • Get results in real-time to catch address typos present in-form, bounce fewer emails, and improve on your email sending reputation-Email Validation.

Also Read: Pepipost SMTP V/S Sendgrid SMTP

4. SendinBlue

Next we have SendinBlue which is also a popular SMTP relay service that is doing great when it comes to email marketing, automation, and transactional emails. It makes business easier by allowing you to complete all your tasks from creating informative emails to sending them via the SMTP relay server. You can use SMTP parameters, API, postfix configuration, and the PHP library of SendinBlue for better integration facilities.


  • SendinBlue ensures domain security and good IP reputation as it provides you with a dedicated IP address.
  • It allows you to execute the deliverability test & access click-through rates, open rates that help in further implementations and analysis.
  • It also has a Send Time Optimization feature so that you can decide the right time to send your emails. 
  • Template gallery and drag & drop Builder that will empower you to inspire your audience by your creativity.

5. Amazon SES

Another in the list is the most affordable SMTP relay service and a very popular product of Amazon.

Amazon SES is a very cost-effective and highly scalable bulk and transactional email-sending service for businesses and developers. You can use their SMTP interface or one of the AWS SDKs to integrate Amazon SES directly into your existing applications.


  • You don’t have to care about feedback loops — Amazon SES will send you an email if someone of your recipients reports your message as spam with the help of a built-in G-Lock EasyMail feature. 
  • With the help of Amazon SES, you can use replacement tags for better content personalization in your email templates.
  • Amazon SES supports all authentication mechanisms, including Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting, and Conformance (DMARC). 
  • Amazon SES provides information about all the metrics for your email campaign, including the numbers of sends,  opens, clicks, bounces etc.

6. Mailgun

Next we have in the list, Mailgun that provides easy SMTP integration for your application. Mailgun offers both comprehensive deliverability features and powerful marketing automation tools with some of the most flexible options available for a good SMTP relay service. With cloud-based SMTP relay service by Mailgun, you can send marketing as well as transactional emails to your entire mailing list without worrying about the deliverability rates.


  • Real-time email tracking and advanced analytics for your emails to make better decisions.
  • You also have access to detailed logs to diagnose email delivery failures.
  • Inbound parsing and routing to manage millions of incoming emails.
  • Email address validation services to improve and clean your mailing list.

7. Postmarkapp

Postmark is another popular SMTP relay service that is known for sending transactional emails alone. They focus completely on email deliverability and speed. This email client provides excellent security with analytics, along with mobile-friendly responsive message events, email templates that can be activated with simple webhooks, etc. It is super simple to just add credentials into a config file and you’re ready to send!


  • You can track emails through the entire lifecycle with custom metadata.
  • It offers 45 days of email logs of emails that are sent, who received them or marked them as spam.
  • It has a globally distributed SMTP servers to help in faster email delivery.
  • Postmark supports TLS to send data securely between your application and their SMTP relay servers.

8. SendPulse

Next we have SendPulse which is also considered one of the most reliable SMTP relay services. It provides hassle-free and reliable email deliverability services. Its integration is supported by 6 different developer frameworks that allow diverse integration options and you can fully integrate their SMTP server into your CMS, CRM, or other system and then send emails from your own application.


  • Your mailings won’t be sent to any addresses on the list of recipients who have unsubscribed, even if they are on your mailing list. This special feature helps to reduce lot of your burden and improves sending reputation.
  • This SMTP relay server sends your emails using a secure SSL connection.
  • This SMTP relay service generates sending reports and delivery error reports which can be easily downloaded.
  • You can minimize the number of emails landing in spam by using SPF and DKIM.

9. Sparkpost

SparkPost is also a very well- known SMTP relay service provider that has a predictive email intelligence platform. You get the real-time data at your fingertips just like other SMTP relay services. Lately, they have also partnered with ActionIQ to improve on the personalization and analytics capabilities. Their pricing structure was decent until last year when Sparkpost increased their pricing which affected a lot of business especially when the email volumes were in millions.


  • They have a Recipient Validation feature to help in email validation and improve deliverability.
  • It provides access to client libraries that supports languages including python, nodejs, PHP, ruby, java etc.
  • You can create custom and personalized emails through the various email templates that are available.
  • Monitor email campaign metrics like bounced, rejected, delayed emails, etc through their dashboard.

10. Elastic Email

The list is incomplete without them, as they have gained great popularity in recent times. Elastic Email provides all the marketing tools that you need to make your email program successful. They allow easy integration to send emails via HTTP API or SMTP relay where you can scale to 100+ million emails per month on their email delivery infrastructure.


  • Create your own campaigns with an intuitive editor
  • Monitor the effect of the entire campaign or watch single steps to improve your flow through their analytics
  • Improve your email delivery rates by verifying your emails through their email verification service.
  • Availability of Elastic Email plugins and 3rd party integrations that will help you according to your business needs.

11. Mandrill

Mandrill has recently been added with MailChimp services now. It is now majorly used by people who are using Mailchimp thus providing an SMTP Relay service or email delivery infrastructure for the same. So, people can get both the Mandrill and Mailchimp for a complete email sending needs. Although many customers feel that it becomes a bit expensive you can still give them a try if you want.


  • The Mandrill servers are distributed globally and so due to this extensive network emails are sent at a fast speed. 
  • One of the influential features of this scalable SMTP relay server includes the use of multiple domains to send out emails, with a single Mandrill account. 
  • You can even customize your message sending options like reverse DNS, adding custom tracking domains, etc.

Wrapping Up

So, which one do you have an eye on?

Have you got the right one according to your business needs?

Well, we have tried to compile the 11 best scalable SMTP Relay service that you can use in 2020 to have a remarkable email marketing campaign and win the heart of your customers!

If you are confused among some of them, then you can try their free tiers to understand how much you are comfortable with the UI, deliverability rates, reliability, budget, etc.

Our suggestion is to start your email campaign right away! Click on the sign-up button at the top and start experiencing the most robust SMTP Relay service. If you have any queries then shoot it on our 24/7 live chat support!

Till then Happy Emailing!


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Written By: Jasmine Handa