Good morning,
Unfortunately the problem is still present, there has been no update of this format by Shopify at the moment.
If you find solutions we are interested 
Topic summary
Core Issue:
When replying to Shopify contact form submissions using Outlook Web App (OWA), emails appear garbled and unreadable in the iPhone Mail app, with overlapping characters and irregular line spacing. The problem does not occur when sending new emails directly to customers.
Investigation Efforts:
- Microsoft support (up to Level 3 engineers) confirmed emails comply with standards and found no issues on their end
- Apple technical support ruled out the Mail app as the source
- Testing with/without signatures and various formatting showed consistent problems
- Issue appears specific to replies sent via Outlook Web App to Shopify form submissions
Key Findings:
- Problem traced to HTML formatting conflicts between Shopify form emails and Outlook
- Affects both old and new themes (including Dawn theme from December 2024)
- Issue first reported in 2022 and remains unresolved
- Shopify, Microsoft, and Apple each deny responsibility
Workarounds Identified:
- Use desktop Outlook app instead of web version (works 100% of the time per testing)
- Reply from computer email client rather than mobile
- Create new email thread instead of replying directly to form submission
Current Status:
No official solution from Shopify. Multiple users continue experiencing the issue across different themes and setups. Discussion remains open with ongoing frustration about lack of resolution.