Email Best Practices

Learn more about Emails Best Practices and How you can ensure Deliverability

1. Avoid shortened URLs

Shortened URLs in an email can often be flagged up as spam. So avoid shortening your URLs.

2. Add a Physical Address in your Footer

Within the footer of your email, add a physical address. This ensures you are compliant with the CAN-SPAM Act of 2003

3. Email Client Maximum Size

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 ClientSending and inbound size limits
Apple Mail (iCloud)20 MB
Gmail25 MB
Outlook/Office 36520 MB (10 MB for Exchange accounts), with up to 150 MB in Office 365
ProtonMail25 MB
Yahoo25 MB
Zoho Mail20 MB

Source: Mailtrap - Recommended Email Size

4. Email Providers Maximum Size

Email providers additional limit the size of emails that can be sent as an outbound email. If your email goes over a certain size, it will not be sent by the provider being used.

Email Sending ProviderSending size limit
Mailgun25 MB
Mailchimp (previously known as Mandrill)25 MB
Sendgrid30 MB

Source: Mailtrap - Email Providers Recommended Email Size

5. Limit Image Sizes

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.

6. Use a Pre-header (Email Preview Text)

Preheader text or "email summary" is the text that shows up next to or below the subject line in the inbox. This increases open rates as it allows your user to be enticed to open the email. Learn about how to add this in our Designing Emails with Drag and Drop and Designing Emails with HTML.

Email ClientLimitClient Type
iOS Outlook74Mobile Email Client
Android Native43Mobile Email Client
Android Gmail24Mobile Email Client
iOS Native82Mobile Email Client
iOS Gmail30Mobile Email Client
Apple Mail33Desktop Email Client
Outlook ‘1338Desktop Email Client
Outlook for Mac ‘1553Desktop Email Client
Outlook ‘1650Desktop Email Client
AOL Mail81Webmail Client
Gmail119Webmail Client
Outlook.com49Webmail Client
Office 36540Webmail Client
Mail.ru64Webmail Client

Source: Email on Acid

7. Avoid Image Only Emails and Add Alt-text to images

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.

8. Use Contrasting Colors

Choose background colors and foreground colors with contrast to ensure your text is legible for those with visual impairments.

Image showing examples of color contrast, as  shown in [Email On Acid Article]( showing examples of color contrast, as  shown in [Email On Acid Article](

Image showing examples of color contrast, as shown in Email On Acid Article

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