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OneSignal is in the process of migrating from a device-centric model (player ID) to a new user-centric data model (OneSignal ID). To learn more, check out the User Model Beta Overview.
Please refer to Version 9 of our documentation for device-centric information.
The following are important features and best practices for OneSignal's email messaging capabilities. Make sure you follow OneSignal's Email Acceptable Use Policy & Code of Conduct to keep your account in good standing and maintain high deliverability.
Common and important features when getting started with email messaging.
Using a subdomain for email communications is a recommended practice in the industry. It improves email credibility and deliverability by isolating email traffic from your primary domain, reducing the risk of spam association.
Subdomains also allow you to have more control over implementing email authentication measures and monitoring performance.
If you already have a list of email addresses, you can Import Email Addresses into your OneSignal App through the Dashboard or API. It's highly recommended to clean your email list before sending to ensure high deliverability.
Also see Email Segmentation Best Practices.
Another way to increase deliverability is to follow a warm up plan by sending a small amount of emails at first and gradually increasing that over time. See Email Warm-Up for details.
Users should be asked for consent or acknowledge that they want emails from you. Once you obtain their email address, it’s recommended to validate that email is correct and used before sending it messages. This ensures that email addresses are real, spelled correctly, and won’t result in a bounce. It helps improve your deliverability.
See Example: Verification, Magic Link, OTP for details.
OneSignal provides different ways to Send Email Messages:
- Use the dashboard for a no-code approach with a drag-and-drop editor or add your own HTML.
- Setup Journeys for easy automation and omni-channel flows.
- For more programmatic approach use our Create notification API with details in Send Transactional Emails guide.
Unsubscribe links shouldn't be "hard to find". You should use accessible, or high contrast, colors and a large enough font that is easy to read (we recommend at least 12px). If a person can't easily see unsubscribe links, ISPs may mark your emails as spam which will affect future deliverability across all your emails. Make sure to follow the recommended syntax when including Unsubscribe Links .
Shortened URLs in an email can often be flagged up as spam. So avoid shortening your URLs.
Within the footer of your email, add a physical address. This ensures you are compliant with the CAN-SPAM Act of 2003
We recommend each image is kept to a 10 MB as a maximum size. This prevents your email from being blocked from the user's email client.
Images you want to be the same aspect ratio, size, and dimensions should be modified before used within the email editor. For example, if you have products showing in a row, and product 1 is 50x50 pixels but product 2 is 100x30 pixels, this will not render the same hight and width. You must modify the images to be the same dimensions before use within the editor.
Preheader text or "email summary" is the text that shows up next to or below the subject line in an inbox or email client. Using a preheader increases open rates and audience engagement as it allows your user to be enticed to open the email.
When creating an email or template, you can include the Preheader Text using the provided field. Preheaders can include text, Data Tags, or emojis.
Preheaders have character limits that vary based on the email client.
|Email Client||Limit||Client Type|
|iOS Outlook||74||Mobile Email Client|
|Android Native||43||Mobile Email Client|
|Android Gmail||24||Mobile Email Client|
|iOS Native||82||Mobile Email Client|
|iOS Gmail||30||Mobile Email Client|
|Apple Mail||33||Desktop Email Client|
|Outlook ‘13||38||Desktop Email Client|
|Outlook for Mac ‘15||53||Desktop Email Client|
|Outlook ‘16||50||Desktop Email Client|
|AOL Mail||81||Webmail Client|
|Office 365||40||Webmail Client|
Source: Email on Acid
Over 3.2 million Americans have a visual impairment or blindness in the US, in 2015. This means emails should not only contain images, as screen readers cannot discern the content of an image, and instead rely on alt-text.
Add alt-text to any image used to ensure accessibility.
Choose background colors and foreground colors with contrast to ensure your text is legible for those with visual impairments.
Email clients tend to limit the size of an inbound email. If your email goes over a certain size, it is highly likely it will rejected and your deliverability rates will be lower than expected.
|Email Client||Sending and inbound size limits|
|Apple Mail (iCloud)||20 MB|
|Outlook/Office 365||20 MB (10 MB for Exchange accounts), with up to 150 MB in Office 365|
|Zoho Mail||20 MB|
Email providers additionally limit the size of emails that can be sent as an outbound emails. If your email goes over a certain size, it will not be sent by the provider being used.
|Email Sending Provider||Sending size limit|
|Mailchimp (previously known as Mandrill)||25 MB|
Avoid too many links in your email.
Avoid using spam trigger words.
Avoid sending email blasts.
Avoid sending lengthy emails.
Personalize your emails.
Keep text to HTML ratio 60:40.
Updated about 2 months ago