Email Troubleshooting

Common Questions About Email Issues and Deliverability

Why are URLs in my email design not working?

This usually happens if your CNAME record is not setup correctly. However, your ESP may have other configurations that need to be setup. Mailgun has a good guide on this here:

Why are buttons in my email design not clickable?

Make sure that your button has a URL specified for it in your email's design. Also, ensure that you're not viewing the email from inside your email client's Spam folder, as the email client may block all link clicks automatically.

What can I do if I am being marked as spam?

Generally, being marked as spam happens when your recipients are reporting your email as spam or moving the email to their spam folder.

Make sure you follow the Email Best Practices guide to reduce spam reports.

You will also want to work with your Email Service Provider to figure out which deny list you are on, and then work with the specific ISPs to get removed from their lists.

Here are some helpful policies and procedures from our supported ESPs:

What do I do if my emails are landing in the spam folder?

The most common reason for emails landing in spam folder is due to poor reputation which can result from a multitude of factors.

Please see our Why do emails go to spam guide for reasons why emails are landing in the spam folder.

Why are Apple Private Relay emails failing?

If you are collecting and sending to Apple private relay emails, you will need to verify your sending domain with your Apple developer account.

Failing to verify your domain within the Apple developer account will lead to dropped emails.

For instructions on how to configure your DNS for Apple Private Relay, you can go to Apple's setup guide to Configure Private Relay Email Service.

Using Email

Does OneSignal Email Messaging work with all email clients?

Generally yes - a lot of work has been put into ensuring maximum compatibility and visual similarity across major email clients including Gmail, Outlook, Yahoo Mail, and more.

How do I add images to my pre-header?

Gmail allows for images in the pre-header aka Deal Annotations and Product Carousels within the Promotions tab. Details can be found on Google's Gmail Developer Portal.

How does unsubscribing work?

See our Unsubscribe Links & Email Subscriptions guide for more details.

How can I resubscribe emails?

See our Unsubscribe Links & Email Subscriptions guide for more details.

Can I send emails to my push notification subscribers?

Yes, but email addresses are not automatically collected when users subscribe to push notifications. You must set the email address within OneSignal before you can send the user an email.

If your app or website collects email addresses, you can use the setEmail method to add an email address into OneSignal.

If your app or website does not collect email addresses, you will need to do so in order to send emails to your push subscribers. See Importing Email Addresses for all options on getting emails into OneSignal.

Can I target emails based on lists or campaigns?

Yes. If you have email lists in CSV format, you can import the lists into OneSignal.

After importing, you'll be able to add Data Tags and create groups of subscribers called Segments, allowing you to send targeted and personalized email messages and campaigns.

Can I use affiliate links in emails?

OneSignal's email delivery is sent through a 3rd party provider such as Mailgun, Mandrill, or Sendgrid. So, both we and you are bound by any policies and limitations of those services.

Here are some helpful articles or policies from our supported ESPs. We recommend reaching out to their support teams if you have a question about their policies for including affiliate links in your emails.

Email Limits - Is there a limit?

Apps on a Free Plan have a monthly limit of 5,000 email sends. This limit resets at the beginning of each calendar month.

Apps on a Paid Plan have a monthly limit of 500,000 email sends. This limit resets based on your account’s specific billing cycle. If you plan to send at higher volumes, please contact Support to ensure no disruption to your service.

Any email campaigns that would put you over your email will not be sent.

What is OneSignal's Email Throughput?

OneSignal generally sends messages at a rate of 1,000 to 5,000 per second to the Email Service Provider. It is up to your ESP to deliver the emails to your users.

OneSignal uses Mailgun for OneSignal Email and Mailgun advertises that they can support up to 15 million emails per hour.

Email Service Providers (ESPs)

Which email service providers are supported by OneSignal?

Currently, Sendgrid, Mailgun, and Mailchimp are supported by OneSignal.

Do I have to pay another provider for email?

If you use the OneSignal Email Setup then OneSignal will manage your email accounts and you do not need to use another email provider.

If you plan to use Sendgrid, Mailchimp, or Mailgun, then you will need to continue to pay your email service provider directly.

Since OneSignal provides both marketing and transactional email capabilities along with user management, segmentation and automation tools, you only need to pay these ESPs the much cheaper transactional email rates, rather than the higher rates typically charged for marketing automation tools.

What are Webhooks? Why does OneSignal require them?

Webhooks are a method for connecting two separate apps and allowing them to share data with each other, and are often used for things like analytics integrations. They are sent from your email service provider to OneSignal to sync email delivery statistics with our platform.

For troubleshooting webhooks with the ESPs we support, see our related FAQ for Webhooks & Why Email Stats Not Detected?.

How do I set up OneSignal if I already have an active Webhook?

You can continue to use your custom/existing webhook, but you'll need to follow the steps in FAQ for Existing Webhooks for how to forward the request to OneSignal's Webhook URLs.

How do I configure my domain for sending email through OneSignal?

See What is DNS Authentication? for more details.