How to Use SMTP to Fix WordPress Contact Form Not Sending Email

Are you looking to improve email deliverability for your WordPress forms? WP Mail SMTP provides you with several solutions (called “mailers”) to choose from to help your emails deliver successfully.

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.


Fixing Email Delivery Issues Using SMTP Mailers

SMTP mailers play an important role in email delivery: authentication. However, each mailer accomplishes this in a slightly different way.

When an email is received by an email provider (like Google, Outlook, etc.), the provider will verify that it seems legitimate before allowing it into a user’s inbox. One of the biggest factors in this process is whether or not the email is authenticated. An email is authenticated if its origin is the same website that it says it’s been sent from.

This information is visible in the emails that are sent to our inboxes, and email providers are always closely monitoring these details. As spam becomes more common (and smarter), email providers are tightening restrictions around which emails make it to your inbox. If an email fails these checks, then it may be marked as spam or blocked from delivery entirely.

By setting up a mailer through WP Mail SMTP, the authentication needed to pass email providers’ tests will be added to each of the outgoing emails from your WordPress site. The way that WP Mail SMTP does this will vary based on which mailer you configure, but the end result is the same: your emails arrive in your users’ inboxes every time.

Selecting and configuring a mailer will also help in cases where server configuration issues prevent deliverability. For example, some hosts’ servers aren’t configured to use WordPress’ built-in mailing function. Since WP Mail SMTP’s mailers replace the default WordPress mailing function, they allow your site to get around any issues like this.

Below, we’ve detailed each mailer option available with WP Mail SMTP, as well as their requirements.

SMTP.com (Recommended)

SMTP com

SMTP.com is an industry leader in email delivery services and is trusted by more than 100,000 businesses worldwide. Setup and integration are straightforward and easy, and it offers in-depth reporting, a high standard of placing emails in subscriber inboxes, and direct phone support for all plans.

  • Cost: Free for 30 days (up to 50,000 emails). However, after your trial period ends, it does require a paid account. You can check out SMTP.com’s pricing page for all plan options.
  • From Email Requirements: You’ll need a domain-specific From Email (e.g., [email protected]) to ensure reliable delivery.
  • Bottom Line: SMTP.com is a recommended mailer because it leads the industry in email delivery. While many similar mailers require an in-depth setup process, SMTP.com has kept things as simple as possible.

For more information on how to set up this mailer, check out our step-by-step setup guide.

Sendinblue (Recommended)

Sendinblue

Sendinblue provides super reliable delivery of your emails and a robust free option for its users. It uses a secure API, and doesn’t require a credit card to set up (unless you’d like one of its paid plans). As a bonus, if you already use Sendinblue for email marketing, you can use your existing account to configure this mailer.

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

For more information on how to set up this mailer, see our step-by-step setup guide.

Mailgun

mailgun

Mailgun is a widely used and well-known solution for email delivery issues. It uses a secure API and offers a 3-month free trial. After that, a (super competitively priced) paid plan is necessary. Mailgun offers options as low as $0.80 USD per 1,000 emails.

  • Cost: Free for 3 months (up to 5,000 emails per month). After that, pricing starts at $0.80 USD per 1,000 emails sent.
  • From Email Requirements: Works with any From Email. However, we definitely recommend using a domain-specific email for maximum reliability.
  • Bottom Line: Mailgun is one of the most reliable mailers around, and has very competitive pricing. However, it does require DNS access to set up.

For more details on how to set up Mailgun, check out our step-by-step setup guide.

SendGrid

sendgrid

SendGrid is a great option that is widely used to dependably send emails. Similar to Mailgun, it uses a secure API and has a free plan for its users. However, unlike Mailgun, you don’t need a credit card to sign up for a free account.

  • Cost: The free plan allows you to send up to 100 emails each day.
  • From Email Requirements: Works with any From Email. However, we recommend using a domain-specific email for maximum reliability.
  • Bottom Line: SendGrid is a super dependable mailer, and its free plan is a great option for smaller businesses. However, it does require DNS access to properly complete the setup process.

For more information on how to set up this mailer, check out our step-by-step setup guide.

Postmark

Postmark

Postmark ensures email delivery through its secure API. The setup process requires you to change your DNS settings to verify your sending domain, and you’ll need the Postmark team to manually approve your account. However, options such as the ability to configure multiple servers and message streams can make this mailer a good solution if you manage more than one website or segment your emails.

  • Cost: The 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. Pricing starts at $10 per month for 10,000 emails per month.
  • 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: Postmark’s developer plan gives you the chance to test it out commitment-free. Although its setup process is a bit more involved than some of the other mailers in this list, its unique features may come in handy for small businesses.

For more information on how to set up this mailer, see our step-by-step setup guide.

Amazon SES

aws

Requirements: You’ll need a paid license for WP Mail SMTP to access the Amazon SES mailer. You’ll also need a credit card in order to complete your account setup with Amazon.

Amazon’s SES mailer in WP Mail SMTP uses Amazon’s API to successfully deliver emails sent out from your site. You can use this service for free for one year, and after that pricing is based on your usage. You will need a credit card to complete your account setup with Amazon, and this mailer requires you to have SSL certification on your site.

  • Cost: Free for your first year, then usage-based pricing applies.
  • From Email Requirements: Any domain-specific email address (i.e., [email protected])
  • Bottom Line: Amazon SES is a secure solution, and it’s free to get started (although you’ll need a credit card). However, the setup is fairly complex. At one stage, you’ll need approval from Amazon’s team. Due to this, we only recommend this mailer for more technically advanced users.

For more information on how to set up this mailer, check out our step-by-step setup guide.

Gmail

google

The Gmail mailer leverages Google’s API to add a layer of security while improving your email deliverability. This mailer will automatically work with your existing Gmail or G Suite account and is completely free.

However, it’s important to note that Google’s API has much more intense restrictions than other mailers we’ve outlined. For instance, it has stricter server requirements that your site needs to meet. If these requirements aren’t met, you’ll need to get in touch with your site’s hosting provider to fix them.

  • Cost: Free. However, Google won’t allow large quantities of emails to be sent through its API. You can find 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.
  • Bottom Line: Gmail’s API offers you free service, so you’ll never need to worry about being charged. However, if you do hit the limit for its API, your emails will simply not be sent. Users also tend to run into more issues with Google’s API than with other API-based mailer options, which can make delivery much less reliable.

For more information on how to set up this mailer, see our step-by-step setup guide.

Outlook / 365

microsoft

Requirements: You’ll need a paid license for WP Mail SMTP to access the Outlook / 365 mailer. You’ll also need a credit card in order to set up an account through Microsoft.

Similar to Google, the Outlook / 365 mailer operates with Microsoft’s own Graph API, adding a layer of security while improving your site’s email deliverability. Outlook does require you to enter a credit card to complete your account setup through Microsoft, but your account is completely free to use.

  • Cost: Free.
  • From Email Requirements: Works only with a Microsoft-based email address (e.g., [email protected], [email protected], or an Office 365 email address)
  • Bottom Line: Microsoft’s API is a super secure (and free) option to resolve email delivery issues. However, the set up process is fairly complicated, and this API can cause minor delays (a few minutes at most, usually) in email deliveries.

For more information on how to set up this mailer, check out our step-by-step setup guide.

Zoho

Zoho Mail logo

Requirements: You’ll need a paid license for WP Mail SMTP to access the Zoho mailer.

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

  • Cost: Zoho offers a “Forever Free” option, as well as several Premium plans with additional features. For more information, you can check out Zoho’s pricing page for all plan options.
  • 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 email deliverability. As a bonus, it also offers an integration with its Zoho CRM to help businesses manage their sales better.

For more information on how to set up this mailer, be sure to check out our step-by-step setup guide.

Other SMTP

smtp

The Other SMTP option is the only mailer that doesn’t use any sort of API. Instead, it uses classic SMTP (Simple Mail Transfer Protocol). Since its setup process is less lengthy than other mailers, this can make things easier for you in the short term.

However, the Other SMTP mailer usually isn’t as convenient in the long term. For instance, if you reset your email’s password at any time, you’d then need to edit the password setting in WP Mail SMTP, too. This mailer is also much more likely to have configuration issues with your server (which your web host would need to fix).

  • Cost: Free.
  • From Email Requirements: Works with any email address, but you’ll need to use the same address site-wide.
  • Bottom Line: This option is not as secure or reliable compared to other mailers, and shouldn’t be the first choice for any site. However, for sites where it’s needed, the setup process is often pretty simple (as long as the site doesn’t have any server-related problems).

For more information on how to set up this mailer, check out our step-by-step setup guide.

Default (Not recommended)

The Default (PHP) option does not use SMTP and will not improve email delivery on your site. This is the same configuration as if you hadn’t installed WP Mail SMTP on your site at all.

Therefore, we do not recommend using this option. If you notice it’s the active selection in your WP Mail SMTP settings, please set up one of the mailers listed above.

That’s it! We hope this helped familiarize you with the SMTP mailer options available with WP Mail SMTP.

Next, would you like to automatically grow your mailing list any time a user submits your form? Be sure to check out our tutorial on how to install and activate the ActiveCampaign Addon for more details.