Hi @Stefania ,
Welcome to our forum!
How did you upload the photo? Insert it into the message body or using it in your signature?
If so, as i know, the cause of this issue lies in the way handles image dimensions in combination with its dpi value. If you’re using Outlook for Microsoft 365 (Version 2007 or later), you can prevent image compression by enabling the following option:
- Go to File > Options > Mail > Editor Options > Advanced.
- Enable: Do not compress images in file.
If it doesn't help, it's suggested that you could refer to this article and try other steps to re-render the image at 96dpi or resize the image to its original dimensions: Images resize and become unsharp upon sending.
(Note: Since the web site is not hosted by Microsoft, the link may change without notice. Microsoft does not guarantee the accuracy of this information.)
Hope to help you!
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