Email formatting is tricky as there is a wide variety of email clients, across many devices. They each support slightly different CSS elements. If a particular email client (for example, Outlook) doesn't support a style you've applied to a section, that section will show up as broken for your readers. Email clients ability to display styling is very outdated in comparison to what a modern browser, like Chrome or Safari, can display.

Because of this, we have to specially transform the code from the block editor into email-ready code. We've put in a lot of work to make our email code lightweight, clean and readable across email browsers. Our code is heavily tested using Litmus and Testi.

To reduce the chances of your email newsletter breaking or appearing as poorly formatted for your readers, we've limited the blocks you're able to use for your emails in the Newsletter custom post type.

In contrast, we haven't limited the blocks in your regular posts or other custom post types because that would mean you can't use those blocks even when publishing a regular post.

As a result, people trying to send a blog post as a newsletter occasionally run into the problem of broken emails because they've used a block that we haven't optimised for email.

Quick guidelines for what we've optimised, and haven't:

1. All our custom Newsletter Glue blocks are optimised for email.

2. Some Gutenberg blocks are optimised for email (see complete list below).

3. No 3rd party plugin blocks are optimised for email.

4. It's worth noting that any blocks that output basic text are likely to work, even if we haven't specifically optimised it. This will be entirely up to you to test.

Default WordPress blocks

Paragraph block

Heading block

List block

Quote block

Code block 

Custom HTML block

Image block

Separator block

Spacer block

Post featured image block

Post date block

Post title block

Twitter - this will display a simplified version of the Twitter embed that's optimised for email.

Spotify - this will display a simplified version of the Spotify embed that's optimised for email.

YouTube - this will display a simplified version of the YouTube embed that's optimised for email.

Custom Newsletter Glue blocks

NG Show/hide block

NG Metadata block

NG Subscriber form block

NG Author byline block

NG Container block

NG Post embed block

Columns block

Latest posts block

Social follow block


If you're encountering formatting problems with your newsletter, it's likely because you're using blocks that are incompatible with email. If they are not on the above list, your email will probably break.

If you're not sure if you're using compatible blocks, here's how you can check: 

1. Click the list view button to view all the blocks you're using.

2. Remember to expand any nested blocks to get a complete list of all the blocks you're using.

3. Check those blocks against the blocks listed in this doc.

4. If you see blocks that are incompatible, delete them and see if the formatting errors resolve.

Block settings

Some plugins don't just add blocks, they also add block settings to all blocks. These additional settings are also not compatible with email. Please avoid using them.

What if I want to use unoptimised blocks for my blog posts, and exclude them from my newsletters?

Simple. You can use our Show/hide block. Add the unoptimised content into your block and toggle on Show in blog post, then toggle off Show in newsletter

This will also work with our Container block.