MailerPress needs an email sending service to deliver your campaigns, automations and system emails (sign-up confirmations, test emails…). MailerPress (free) sends with PHP Mail or your own Custom SMTP server (SMTP is the standard protocol for sending email). MailerPress Pro adds API connections (a direct link to the service, authorized from your account) to dedicated services such as Brevo, SendGrid, Amazon SES, Mailgun or Gmail.
Supported sending services
Services that require MailerPress Pro appear only when MailerPress Pro is installed and active. Names match the cards in MailerPress. A bounce is an email returned as undeliverable (for example, the address doesn’t exist). MailerPress detects bounces through a webhook (a URL the service calls to notify MailerPress) or by reading a mailbox over IMAP.
| Service | Plan | Bounce tracking | Setup guide |
|---|---|---|---|
| PHP Mail | MailerPress (free) | No | No setup needed (default service) |
| Custom SMTP | MailerPress (free) | Yes, through an IMAP mailbox | Send emails with a custom SMTP server |
| WordPress Default | MailerPress Pro | Yes, webhook of the service used by your SMTP plugin | WordPress Default provider |
| Gmail (Gmail / Google Workspace) | MailerPress Pro | No | Send emails with Gmail |
| Brevo | MailerPress Pro | Yes, webhook | Brevo |
| SendGrid | MailerPress Pro | Yes, webhook | SendGrid |
| Amazon SES | MailerPress Pro | Yes, Amazon SNS notification | Amazon SES |
| Mailgun | MailerPress Pro | Yes, webhook | Send emails with Mailgun |
| Mailjet | MailerPress Pro | Yes, webhook | Send emails with Mailjet |
| PostMark | MailerPress Pro | Yes, webhook | Postmark |
| Resend | MailerPress Pro | Yes, webhook | Resend |
| SMTP2GO | MailerPress Pro | Yes, webhook | SMTP2GO |
| Emailit | MailerPress Pro | Yes, webhook | EmailIt |
| ToSend | MailerPress Pro | Yes, webhook | Send emails with ToSend |
| Postal server | MailerPress Pro | Yes, webhook | Send emails with Postal |
PHP Mail sends from your web server: emails often land in spam or are blocked by hosts. Use it only for testing or very small lists.
Connect a sending service
All services are configured in MailerPress > Integrations, on the Email Service Providers tab. The cards are grouped in three sections:
- Configured Providers: services you have already set up, with an Active or Inactive status.
- Recommended Providers: Brevo, SendGrid and Amazon SES, until they are configured.
- Other Providers: all other services not configured yet.
To connect a service:
- Click Configure on the service card.
- Fill in the credentials the service asks for (API key, which is a secret code identifying your account, SMTP server, OAuth client…) and, for most services, a Default sender email address and a Default sender name. The service must allow this sender address (verified domain or sender).
- Click Save changes. The card moves to Configured Providers.
- Turn on the Enable toggle on the card.
- Click Set as primary provider. The card now shows a Primary badge.
Only the primary provider sends your emails. You can keep several services configured and switch at any time with Set as primary provider, or with Set as primary in the three-dot Actions menu. To change the credentials later, click Configure on the card, or Settings in the Actions menu.
If MailerPress shows Your primary provider is disabled., the primary service has been turned off: enable it again or set another active service as primary. Without an active service, MailerPress cannot send emails.
Send a test email
Test each service before sending a campaign:
- Make sure the service is enabled. The test isn’t available while the card is inactive.
- Open the three-dot Actions menu of the card and click Send test email.
- Enter the recipient in Send to, keep or turn off the HTML toggle, and click Send.
You should receive an email with the subject “This is a Sending Method Test”. If sending fails, MailerPress shows Failed to send test email with the error returned by the service (invalid API key, unverified domain, SMTP connection refused…).
Adjust the sending speed
MailerPress sends campaigns in batches (a set number of emails at regular intervals). Go to MailerPress > Settings > Sending frequency, or click Adjust sending frequency on the primary provider card. The profiles offered depend on your primary service. Recommended profiles:
| Service | Recommended profile | Batch and interval |
|---|---|---|
| PHP Mail | Prudent (Recommended for shared hosting) | 25 emails every 10 minutes |
| WordPress Default | Conservative (safe for most SMTP plugins) | 25 emails every 10 minutes |
| Custom SMTP | Balanced (Recommended – Most SMTP servers) | 50 emails every 5 minutes |
| Gmail | Free Gmail (500/day limit) | 20 emails every 10 minutes |
| Brevo, SendGrid, Amazon SES, Mailgun, Mailjet, PostMark, Resend | Balanced (Recommended) | 75 emails every 5 minutes |
| ToSend | Balanced (Recommended) | 100 emails every 5 minutes |
| SMTP2GO, Emailit | Balanced (Recommended) | 100 emails every 2 minutes |
| Postal server | No predefined profile | Use the Manual mode |
Each service also has lighter and faster profiles: see How to change your sending frequency in MailerPress for all profiles and the manual settings. Always stay within your plan’s limits with the sending service.
Track bounces
Bounce tracking flags addresses that can’t receive your emails, so you stop sending to them. Set it up in each service’s settings, below the credentials:
- API services (MailerPress Pro): turn on Enable bounce tracking, copy the webhook URL shown by MailerPress and add it to your service’s webhook settings. For Amazon SES, add it as an Amazon SNS endpoint (Amazon’s notification service).
- Custom SMTP (free): turn on Enable bounce tracking (IMAP) and connect a mailbox that receives bounce messages. MailerPress checks it regularly.
- WordPress Default (MailerPress Pro): choose the Bounce tracking provider used by your SMTP plugin and add the webhook URL in that provider’s dashboard.
- PHP Mail and Gmail: no bounce tracking.
A bounced contact gets the Bounced status and no longer receives campaigns, which go to subscribed contacts only. To see them, go to MailerPress > Audience > All Contacts and click the Bounced tab.
Which service should you choose?
- You use MailerPress (free): connect a custom SMTP server from your host or email provider rather than PHP Mail.
- You already use an SMTP plugin (WP Mail SMTP, Fluent SMTP…): with MailerPress Pro, the WordPress Default provider lets that plugin deliver MailerPress emails.
- You send a small volume from a Google account: Gmail works, but Google limits sending to about 500 emails a day for a free Gmail account and 2,000 for Google Workspace.
- You send newsletters regularly: use a dedicated service with an API connection and bounce tracking (Brevo, SendGrid, Amazon SES, Mailgun, Mailjet, Postmark…).
Whatever the service, verify your sending domain with it (SPF and DKIM records: DNS entries you add at your domain registrar or host to prove the service may send for your domain) and use a sender address on that domain. To set the default sender of your campaigns, see Customize the default sender name and email address.