# SendGrid

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

Connect CRM-NG SMTP to SendGrid with a Mail Send API key and an authenticated sending domain.

This guide shows you how to send your WordPress email through SendGrid, a large transactional email service run by Twilio. It suits sites of any size, from a contact form to a busy shop. SendGrid's entry-level options change from time to time; check its plans page for what is currently free or on trial.

 

The **SendGrid** mailer sends through SendGrid's API with an API key. The key needs only one permission, **Mail Send**. You also prove to SendGrid that you own the address or domain you send from.

 

## Before you start

 
- A SendGrid account (sign up at `https://sendgrid.com/`). New accounts may be reviewed before they can send.
- A domain you control, with access to its DNS records. A single verified address works for testing, but a domain gives far better delivery.
- Administrator access to your WordPress site.

 

## Setup

 

### Step 1: Authenticate your domain

 
1. Sign in to SendGrid
  Go to `https://app.sendgrid.com/` and sign in.
2. Open Sender Authentication
  Open **Settings → Sender Authentication**.
3. Start domain authentication
  Choose **Authenticate Your Domain**, pick your DNS provider (or "Other"), and enter your domain. You can use a subdomain such as `mail.yourdomain.com` if you prefer.
4. Publish the records
  SendGrid shows several CNAME records. Add them at your DNS provider exactly as shown.
5. Verify
  Return to SendGrid and press **Verify**. When it succeeds, any address on that domain can send.

 

If you cannot change DNS yet, use **Single Sender Verification** on the same page to verify one address by email. Your **From Email** must then be exactly that address.

 

### Step 2: Create an API key with Mail Send access

 
1. Open API Keys
  Open **Settings → API Keys** (the plugin's **Create API Key** link goes to `https://app.sendgrid.com/settings/api_keys`) and choose **Create API Key**.
2. Name it
  Use a name that identifies the site, such as "yourdomain.com WordPress".
3. Restrict it
  Choose **Restricted Access**. In the list of permissions, set **Mail Send** to full access and leave the rest off. The plugin only needs this access level.
4. Copy the key
  Press **Create & View** and copy the key, which starts with `SG.`. SendGrid 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 **SendGrid**.
2. Paste the key
  Paste the key into **API Key**.
3. Enter the sending domain
  In **Sending Domain**, type the domain or subdomain you authenticated in SendGrid, for example `mail.yourdomain.com`. CRM-NG SMTP uses it for the domain check after a test email; leave it empty if you only verified a single sender.
4. Set the sender
  Set **From Email** to an address on the authenticated domain (or your single verified sender) and set **From Name**. Tick **Force From Email** so other plugins cannot send from an unverified address.
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**. In SendGrid, **Activity** shows the message and whether it was delivered. See [Sending a test email](https://catalystgroup.gg/docs/email-delivery/send-a-test-email/).

 

The test page's domain check looks for `sendgrid.net` in your SPF record. With domain authentication set up, SendGrid handles SPF through its CNAME records, so focus on DKIM and DMARC passing. See [Adding DNS records](https://catalystgroup.gg/docs/email-delivery/dns-records/).

 

## Troubleshooting

 
- The key is wrong, revoked, or lacks Mail Send: [Authorization grant invalid or expired](https://catalystgroup.gg/docs/email-delivery/error-sendgrid-authorization-grant-invalid/)
- The From Email is not verified in SendGrid: [From address does not match a verified Sender Identity](https://catalystgroup.gg/docs/email-delivery/error-sendgrid-sender-identity-mismatch/)
- The account is under review or limited: [Authenticated user not authorized to send](https://catalystgroup.gg/docs/email-delivery/error-sendgrid-user-not-authorized/)
- Access refused in general: [401 Unauthorized or Forbidden](https://catalystgroup.gg/docs/email-delivery/error-401-unauthorized-or-forbidden/)
- The recipient bounced before and is blocked: [Email address in suppression list](https://catalystgroup.gg/docs/email-delivery/error-email-in-suppression-list/)
- Your plan's limit is used up: [Email sending limit reached](https://catalystgroup.gg/docs/email-delivery/error-email-sending-limit/)
- 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/)
- [Delivery and bounce webhooks](https://catalystgroup.gg/docs/email-delivery/delivery-webhooks/)
- [Sender name, address and the Force settings](https://catalystgroup.gg/docs/email-delivery/sender-name-and-address/)
- [Securing settings with wp-config constants](https://catalystgroup.gg/docs/email-delivery/secure-settings-constants/)