Images distorted in Jetpack Newsletters on Apple Mail

### Impacted plugin

Jetpack

### Quick summary

Images in blog posts using the single image block are distorted when viewed in Jetpack Newsletters on the Apple Mail app. The images do not scale responsively, resulting in distortion. Below can be seen a comparison of the same image from a newsletter, how it looks like in the Gmail app vs Apple Mail app on iOS:

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Internal discussion: p1722872265280389-slack-C0CMN0V97
Forum: https://wordpress.org/support/topic/images-distorted-in-newsletters/

### Steps to reproduce

1. Set up a new test site or use an existing one.
2. Enable Jetpack Newsletter.
3. Subscribe to the newsletter on that site.
4. Create a test post and include images using the Image Block, including at least one portrait-oriented image.
5. Publish the post to trigger the newsletter.
6. Check the registered email for the newsletter and review the images for any distortion issues.

### A clear and concise description of what you expected to happen.

The images should scale responsively, maintaining their aspect ratio, without appearing squeezed or distorted regardless of the app used to open the email.

### What actually happened

Images appear squeezed and distorted when viewed in the Apple Mail app

### Impact

Some (< 50%)

### Available workarounds?

No and the platform is unusable

### Platform (Simple and/or Atomic)

_No response_

### Logs or notes

Reproduce the issue using Jetpack Newsletter, a post with the Image Block, and a portrait-oriented image, then compare the newsletter in Apple Mail and Gmail on iOS. Trace the newsletter email rendering for single image blocks; done means images retain their aspect ratio and scale responsively in Apple Mail without regressing other clients.

Written by the indexing model from the issue text.