If your logo shows as a broken image or does not appear at all in your automated emails, the cause is usually one of three things. They are listed here in order of how often they happen.
The logo field has a page address instead of an image URL. The logo field needs a direct image URL that points at the image file itself, ending in something like .png or .jpg. If you paste your website address, or a link to the page the logo appears on, the email shows a broken image. The reliable way to get the right URL is to upload your logo to the WordPress Media Library and copy the file URL from there.
The logo is an SVG. SVG logos do not work in email. Many email clients strip SVG images entirely, so an SVG that looks correct on your website shows as nothing in an inbox. Use a PNG or JPG version for email, even if your site itself uses SVG.
The logo is white or reversed. The email layout puts content on a white card. A logo designed for a dark website header is usually white or light, and it becomes invisible against that white background. Use a version with dark or full-color artwork for email.
Check the URL for typos. Double-check the domain in the URL. A single wrong character produces a broken image with no other symptom.
If you do not have a suitable logo file yet. Leaving the logo field empty is better than leaving a broken or invisible logo. The email falls back to showing your business name as text and adjusts its spacing accordingly, so it looks intentional rather than broken.