# MailerSend

Source: https://catalystgroup.gg/docs/email-delivery/mailer-mailersend/
Updated: 2026-10-19 · By Duane Garner

Connect CRM-NG SMTP to MailerSend with an API token and a verified domain, and understand the trial account limits.

This guide shows you how to send your WordPress email through MailerSend, a modern transactional email service. It suits sites that want a clean dashboard and a generous free allowance to start. MailerSend's free plan includes a monthly quota; check its site for the current figure.

 

The **MailerSend** mailer sends through MailerSend's API with an API token. MailerSend only sends from domains you have verified, and new accounts start with trial limits.

 

## Before you start

 
- A MailerSend account (sign up at `https://www.mailersend.com/`).
- A domain you control, with access to its DNS records.
- Administrator access to your WordPress site.

 

> **Trial limits:** Until you verify a domain and your account is approved, MailerSend treats it as a trial: it sends only to the email address of the account's administrator, with a small quota. Plan to finish domain verification before going live.

 

## Step 1: Add and verify your domain

 
1. Sign in to MailerSend
  Go to `https://app.mailersend.com/` and sign in.
2. Open Domains
  Open **Domains** from the side menu and choose **Add domain**.
3. Enter your domain
  Type the domain you send from, for example `yourdomain.com`.
4. Publish the records
  MailerSend lists records for SPF (TXT), DKIM and a return path (CNAME). Add them at your DNS provider exactly as shown.
5. Verify
  Return to MailerSend and press **Verify** until the domain shows as verified.

 

See [Adding DNS records](https://catalystgroup.gg/docs/email-delivery/dns-records/) for help with DNS.

 

## Step 2: Create an API token

 
1. Open API tokens
  Open the API tokens page (look under **Integrations → API tokens**, or use the plugin's **Get API Key** link, which goes to `https://app.mailersend.com/api-tokens`).
2. Generate a token
  Choose **Generate new token**, name it after your site, and pick the domain it may send for.
3. Set the access
  Give it full access to email sending, or choose custom access and allow at least email sending.
4. Copy the token
  Copy it now. MailerSend shows it once.

 

## Step 3: Connect in CRM-NG SMTP

 
1. Choose the mailer
  In WordPress, open **CRM-NG SMTP → Settings → General** and set **Mailer** to **MailerSend**.
2. Paste the token
  Paste the token into **API Key**.
3. Set the plan option
  Turn on **Professional Plan** only if your MailerSend plan allows custom email headers. While it is off, CRM-NG SMTP leaves custom headers out of each message, which is what lower plans need. Turning it on with a plan that lacks the feature can make MailerSend refuse messages.
4. Set the sender
  Set **From Email** to an address on your verified domain and set **From Name**. Tick **Force From Email** so other plugins cannot use an unverified domain.
5. Save
  Press **Save Settings**.

 

## Send a test email

 

Open **CRM-NG SMTP → Tools → Email Test**, enter your address in **Send To**, and press **Send Email**. While on a trial, send to the administrator address of your MailerSend account. MailerSend's **Activity** page shows the result. See [Sending a test email](https://catalystgroup.gg/docs/email-delivery/send-a-test-email/).

 

## Troubleshooting

 
- The account is still on trial and the recipient is someone else: [Trial accounts can only send to the admin address](https://catalystgroup.gg/docs/email-delivery/error-mailersend-trial-accounts/)
- The From domain is not verified: [Domain not verified](https://catalystgroup.gg/docs/email-delivery/error-mailersend-domain-not-verified/)
- The token is wrong, deleted, or not allowed for this domain: [Unauthenticated](https://catalystgroup.gg/docs/email-delivery/error-mailersend-unauthenticated/)
- Your monthly quota is used up: [Email sending limit reached](https://catalystgroup.gg/docs/email-delivery/error-email-sending-limit/)
- The recipient bounced before and is blocked: [Email address in suppression list](https://catalystgroup.gg/docs/email-delivery/error-email-in-suppression-list/)
- Mail arrives in spam: [Emails landing in spam](https://catalystgroup.gg/docs/email-delivery/emails-landing-in-spam/)

 

## Related

 
- [Choosing a mail service](https://catalystgroup.gg/docs/email-delivery/choose-a-mailer/)
- [Adding DNS records: SPF, DKIM and DMARC](https://catalystgroup.gg/docs/email-delivery/dns-records/)
- [Verifying your DNS records](https://catalystgroup.gg/docs/email-delivery/verify-dns-records/)
- [Sender name, address and the Force settings](https://catalystgroup.gg/docs/email-delivery/sender-name-and-address/)
- [Debug events](https://catalystgroup.gg/docs/email-delivery/debug-events/)