How to fix emails not sending

This tutorial will show you how to fix emails not sending or only sending to a portion of your subscribers.

Fix emails only sending to a few subscribers

Check sending limits

First, check if your host (or email sender) has email-sending limits.

If they do, inquire about their hourly limits then set it via Noptin > Settings > Emails > Emails Per Hour.

Monitor errors

Second, check Noptin > Tools > Debug Log and see if any errors are logged.

If they are, try to fix the errors or contact us and we’ll walk you through how to fix it.

Are you using an SMTP service?

Third, if you’re using an SMTP service or third-party email sender then contact them and see if they only allow sending emails to verified contacts.

If they do, you’ll need to upload your Noptin contact to their service before sending your email.

Use a mail-logging plugin

WordPress’ email sender might return false even though an email was sent. In this case, Noptin won’t log the email as sent, hence the number of recipients shown on the email campaigns page will be less than the actual number.

To check, install a mail logging plugin and count how many emails are logged after you publish a newsletter.

Fix emails not sending at all

First, open any Noptin email campaign in the campaign editor and send yourself a test email.

If the email is not delivered then your WordPress site is not properly configured to send emails.

The best way to fix this is by using an SMTP server.

What is an SMTP Server?

SMTP stands for Simple Mail Transfer Protocol, and it is the standard communication protocol used for sending emails across the internet.

SMTP services are essential for email transmission and are used by email servers to send, receive, and relay outgoing mail between email senders and receivers.

Why use an SMTP Server?

SMTP servers provide the following advantages compared to sending your Noptin emails directly via your WordPress site:-

Improved Deliverability

SMTP servers are specifically designed to send emails, ensuring higher deliverability rates.

They handle emails in a way that is more likely to be accepted by recipient email servers and less likely to be marked as spam.

Authentication and Security

SMTP services often include authentication mechanisms like SPF, DKIM, and DMARC, which verify the sender’s identity and improve email security.

These features help protect against phishing and spoofing attacks.


SMTP services can handle a large volume of emails efficiently, making them suitable for websites with many newsletter subscribers and high email traffic.

Error Handling

SMTP servers provide better error handling and reporting, giving you insights into why certain emails may not have been delivered.

The table below lists some of our recommended SMTP service providers and their prices.

NOTE: The prices were last updated on February 29, 2024.

SMTP Service ProviderMonthly Cost (Approx.)Notable Features
SendGridFree plan available; paid plans start around $19.95/monthComprehensive deliverability features, scalable, well-documented API
MailgunFree plan available; paid plans start around $35/monthEmail validation, detailed analytics, flexible API
Amazon SES$0.10 per 1,000 emails sent + data transfer feesHighly scalable, cost-effective, integration with AWS services
SMTP.comPlans start around $25/monthHigh deliverability, reputation defender feature, 20+ years in email delivery
PostmarkFree plan available; paid plans start around $15/monthFocus on transactional emails, fast delivery, detailed analytics
MailjetFree plan available; paid plans start around $15/monthIntuitive email builder, A/B testing, segmentation
BrevoFree plan available; paid plans start around $25/monthEmail marketing, transactional emails, CRM features
List of recommended SMTP services

Building your own SMTP service

If you send thousands of emails per month then it might be cheaper to build your own SMTP service instead of using a third-party server.

This also gives you more customization options and enhances data privacy, security, and reliability.

For this, we recommend you use Mail-in-a-Box. You can easily set it up on a DigitalOcean droplet and start using it right away.

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