A Complete Guide to WP Mail SMTP Mailers

Are you trying to decide the best way to improve email deliverability for your WordPress site? WP Mail SMTP provides you with several options called “mailers” to let you choose the specific tool that will help deliver your emails successfully to users’ inboxes.

In this guide, we’ll share a quick overview of each mailer in WP Mail SMTP so that you can more easily decide which is the best fit for your site.


How Do WP Mail SMTP Mailers Fix Email Delivery Issues?

While each mailer in WP Mail SMTP works differently, they all serve an important function: authentication.

When an email provider (like Google, Outlook, etc.) receives a new email, it will check to see if that email seems legitimate. One of the most important things it does during this process is look to see whether the email has been authenticated. In other words, email providers check if each email was actually sent from the site that it claims it was sent from.

Most of us never see this information in the emails we receive, but our email providers are checking over these details very carefully. And as the spamming industry continues to grow (and get more clever), providers are becoming even more strict about which emails they’ll allow into users’ inboxes. If an email doesn’t pass these checks, then it may end up in the recipient’s spam folder or simply never get delivered at all.

When you set up a mailer in WP Mail SMTP, it will authenticate each of your emails. The exact method used will depend on which mailer you choose, but the target result is the same: authenticating your emails so that they arrive in users’ inboxes successfully.

Setting up a mailer will also help in cases where emails can’t be sent properly because of server configuration issues. For instance, some servers aren’t set up to use the WordPress mailing function. Since WP Mail SMTP mailers replace the default WordPress mailing function, they allow your site to get around any issues like this.

Each mailer has a different approach to solving your site’s email delivery issues, and also different requirements. In the sections below, you can check out a quick overview of each mailer in WP Mail SMTP to determine which option is the best fit for your WordPress site.

SMTP.com

SMTP com

Note: SMTP.com is a recommended mailer.

SMTP.com has been improving email delivery for over 20 years and has a strong reputation for reliability. It offers a free trial, after which a paid account is required. However, its pricing options are competitive, and importantly, its setup process is fairly simple compared to many similar services.

  • Cost: Free for up to 50,000 emails in the first 30 days. After this trial period, a paid account is required. You can check out SMTP.com’s pricing page for all its plan options.
  • From Email Requirements: For reliable email delivery, you’ll need a domain-specific From Email (e.g., [email protected]).
  • Bottom Line: SMTP.com is a recommended mailer because it’s an industry leader for email delivery. While many similar services require a pretty extensive setup process, SMTP.com has kept its requirements as simple as possible.

Get Started with SMTP.com

Check out our step-by-step setup guide for the SMTP.com mailer.

Sendinblue

Sendinblue

Note: Sendinblue is a recommended mailer.

Sendinblue offers reliable email delivery services as well as a generous free plan. This mailer uses a secure API, and as an added bonus, you won’t have to enter a credit card to complete the setup process (unless you decide you’d like a paid plan). If you already use Sendinblue for its email marketing services, then you can use the same account to set up this mailer.

  • Cost: Free for up to 300 emails per day. It also has a wide variety of paid plans with higher monthly limits. Please check out Sendinblue’s site for more details.
  • From Email Requirements: Works with any From Email, but we strongly recommend using a domain-specific email for greater reliability.
  • Bottom Line: Sendinblue is a recommended mailer because of its easy setup. It has a solid free option with no credit card required, and most importantly, its services are reliable.

Check out our step-by-step setup guide for the Sendinblue mailer.

Mailgun

mailgun

Mailgun is a popular and super reliable tool for improving email delivery. It also uses a secure API and has a 3-month free trial.

After that trial period, a paid account is required. However, its pricing is super competitive (as low as $0.80 USD per 1,000 emails). It’s also worth noting that you’ll need a credit card to create a Mailgun account.

  • Cost: Free for up to 5,000 emails per month during your first 3 months. After that, pricing options start at $0.80 USD per 1,000 emails sent.
  • From Email Requirements: Works with any From Email, but we highly recommend using a domain-specific email for best reliability.
  • Bottom Line: Mailgun is one of the most reliable email delivery options around, and has super competitive pricing. However, it does require DNS (Domain Name System) access to set up.

Check out our step-by-step setup guide for the Mailgun mailer.

SendGrid

sendgrid

SendGrid is a solid service commonly used to reliably send emails. Much like Mailgun, it uses a secure API and offers a free plan. Unlike Mailgun, no credit card is required when initially signing up for a free account.

  • Cost: Free to send up to 100 emails each day.
  • From Email Requirements: Works with any From Email, but we recommend using a domain-specific email for the greatest reliability.
  • Bottom Line: SendGrid is a super reliable option, and offers a free plan that works well for smaller businesses. It’s worth noting that it requires DNS access to properly authenticate your domain and complete the setup process.

Check out our step-by-step setup guide for the SendGrid mailer.

Postmark

Postmark

Postmark prides itself on its reliable email delivery services. Using its secure API, you can authenticate emails from your sending domain. You’ll need to verify this domain by adding DNS records to your DNS settings and will also need to have your account manually approved by the Postmark team. However, Postmark includes unique features like message streams, which can be useful for managing your email segmentation strategy.

  • Cost: Postmark’s free developer plan allows you to send 100 emails per month. To send more than that, you’ll need to invest in a paid plan. See Postmark’s pricing page for more details.
  • From Email Requirements: Works with any From Email, as long as you first verify it in your Postmark account. However, we recommend using a domain-specific email address for maximum reliability.
  • Bottom Line: With its free developer plan, Postmark is an affordable mailer to get started with. Its setup process is a little more involved than some of the other options, but its reputation for reliable email delivery and its advanced features may outweigh the extra steps needed to configure it.

Check out our step-by-step setup guide for the Postmark mailer.

Amazon SES

aws

The Amazon SES mailer in WP Mail SMTP leverages Amazon’s API to successfully deliver emails sent from your site. This service is free for your first year, then pricing is based on usage. A credit card is required to complete your Amazon SES account setup, and your site must have an SSL certificate installed to use this mailer.

  • Cost: Free for the first year, then Amazon applies usage-based pricing.
  • From Email Requirements: Works with any domain-specific email address (e.g., [email protected])
  • Bottom Line: Amazon SES is secure and free to get started (though you’ll need a credit card to set up your account). However, the setup process is fairly involved and, at one stage, requires approval from Amazon’s team. As a result, we only recommend this mailer for more technically advanced users.

Check out our step-by-step setup guide for the Amazon SES mailer.

Gmail

google

The Gmail mailer uses Google’s API to securely improve email deliverability. It’s free and works with your existing Gmail or G Suite account.

However, Google’s API tends to have more restrictions than the mailers listed above. For example, it has some strict server requirements. If your site doesn’t meet these requirements, you’ll need to contact your hosting provider to resolve any issues.

  • Cost: Free. Please note, though, that Google simply won’t allow large numbers of emails to be sent with its API (you can check out more details on Google’s email limit page).
  • From Email Requirements: Works with Gmail addresses, G Suite email addresses, Google Workspace aliases, or Gmail aliases at a custom domain. Please see our full tutorial on configuring the Gmail mailer with an alias for more details.
  • Bottom Line: Gmail’s API only offers a free service, so you don’t have to worry about getting charged at any point. However, if you do hit its limits then it simply won’t send your emails. Its API also tends to run into more issues than the other API-based mailer options, which can make it less reliable.

Check out our step-by-step setup guide for the Gmail mailer.

Outlook / 365

microsoft

The Outlook / 365 mailer in WP Mail SMTP uses Microsoft’s Graph API to securely improve the deliverability of your site’s emails. A credit card is required to complete your account setup with Microsoft. However, it’s free to use your account for better email delivery.

  • Cost: Free.
  • From Email Requirements: Works only with Microsoft-based email addresses (e.g., [email protected], [email protected], and Office 365 emails)
  • Bottom Line: Microsoft’s API is a secure option and free to use for email delivery. However, the setup process is fairly involved, and this API tends to cause minor delays (a couple of minutes at most) in email deliveries.

Check out our step-by-step setup guide for the Outlook / 365 mailer.

Zoho

Zoho

Zoho offers secure and reliable email delivery services through its API, and you won’t have to enter a credit card to complete your account setup (unless you decide you’d like a paid plan). This mailer also places emphasis on its data security strategies, which include a network security system that uses the latest encryption technologies.

  • Cost: There is a “Forever Free” option, as well as several paid plans with additional features. For more information, you can check out Zoho’s site for all plan details.
  • From Email Requirements: Works with any From Email, but we highly recommend using a domain-specific email for best reliability.
  • Bottom Line: Zoho is a reliable option for anyone looking to improve their site’s email deliverability. As a bonus, it also offers an integration with its Zoho CRM to help businesses manage their sales better.

Check out our step-by-step setup guide for the Zoho mailer.

Other SMTP

smtp

Other SMTP is the only mailer in WP Mail SMTP that does not use an API. Instead, it uses traditional SMTP (Simple Mail Transfer Protocol). This can be convenient in the short term because it requires fewer steps to set up.

However, this mailer tends to be less convenient in the long term. For example, you’ll need to edit your mailer password setting any time you change your email account’s password. It’s also more likely to run into server configuration issues, which you would need your web host’s help to fix.

  • Cost: Free.
  • From Email Requirements: Works with any email address. However, you’ll need to use the same From Email site-wide.
  • Bottom Line: This should not be the first choice mailer for any site, as it’s less secure and less reliable than the other mailers. For those sites where it’s needed and there aren’t server-related issues, though, the setup is often pretty quick.

Check out our step-by-step setup guide for the Other SMTP mailer.

Default (none)

Lastly, you may be wondering about the Default (none) option. The Default (none) option does not use SMTP and will not improve email delivery on your site. It’s essentially the same as not using WP Mail SMTP on your site at all.

So, if you see this option in your WP Mail SMTP settings, be sure to choose one of the other mailer options instead. You can find links to step-by-step tutorials for each above.

That’s it! We’ve just shared an overview of all of the mailer options in WP Mail SMTP.

Would you prefer to let our team do the work of setting your mailer up for you? Be sure to check out our White Glove Setup option, where we handle your WP Mail SMTP plugin setup and testing.