Outlook Mobile to Desktop Draft Sync Causes Garbled Characters (Encoding Issue)

Question

Hello Microsoft Team,

I'm facing a recurring issue when drafting emails using the Outlook mobile app (on both Android and iOS), which leads to garbled or unreadable characters after sending the email from my Windows desktop Outlook client.

Issue Summary:

I use a OnePlus Nord CE (Android) and iPhone 15 Pro (iOS) with the Outlook mobile app.

When I start composing an email in the mobile app and minimize it (so it's saved to Drafts), I later open and send the same draft from my Outlook desktop app (Windows 11, latest build).

Upon sending, the email content gets replaced by corrupted text—often containing Chinese or Japanese-like characters.

This corrupted version appears in my Sent Items, and the recipient also sees the same garbled text.

The issue occurs across both Android and iOS devices and only when the draft is sent from the desktop Outlook app.

Example of corrupted text (partial):

浴浸湬㩳㵶產湲猺档浥獡洭捩潲潳瑦挭浯瘺汭•浸湬㩳㵯...

This appears to be base64 or UTF-16 encoded content misinterpreted as plain text or ASCII, potentially due to encoding mismatches between the mobile and desktop Outlook apps.

Troubleshooting Done:

Tested on multiple devices (Android and iOS).

Confirmed the issue is not limited to one account or device.

Latest versions of Outlook are installed on all platforms.

Windows system is up to date.

Email is sent using a Microsoft 365 account.

Request:

Please investigate this potential encoding/rendering bug between Outlook mobile and Outlook desktop clients when handling saved drafts. It impacts the reliability of cross-platform drafting and can result in unreadable or corrupted communications.

Thanks,

Answer 1

This is a problem I have had too. It's really bad customer support to say "well, just don't do that then" when a person who's using your email app across platforms (as designed and advertised!) is having a problem that's an obvious tech problem on your side. Way to capture the market and then make things progressively worse.

Answer 2

Hello Jubin Fernandes

Thank you so much for reaching out and for sharing such clear details about the issue you're experiencing. We completely understand how important it is for your emails to work smoothly across devices, and we truly appreciate the time you've taken to look into this already. 

From what you've described, the issue occurs when an email is drafted in the Outlook mobile app (on Android or iOS), saved to Drafts, and later sent from the Outlook desktop client on Windows 11. When sent, the content appears garbled—often showing unreadable characters resembling Chinese or Japanese script. This affects both the Sent Items and the recipient’s inbox. 

This behavior is likely due to differences in how the Outlook mobile and desktop clients handle text encoding. Drafts saved on mobile may use encoding formats such as UTF-16 or Base64, which may not be interpreted correctly by Outlook on desktop during sending. 

To help resolve and prevent this issue, we’d recommend trying the following steps: 

Configure UTF-8 Encoding in Outlook Desktop 

To ensure consistent character rendering, we recommend setting UTF-8 as the preferred encoding for outgoing messages: 

• Go to File > Options > Advanced > International Options 
• Under International options, select Unicode (UTF-8) for Preferred encoding for outgoing messages. 

Avoid Sending Mobile Drafts from Desktop 

The most reliable way to prevent this issue from recurring is to avoid starting a draft on one platform and sending it from another. 

• If possible, send emails from the same platform on which they were originally drafted. 
• Alternatively, if you must send from the desktop, copy the content of the mobile-saved draft into a brand-new email within Outlook for Windows, rather than directly sending the original draft. 

Ensure HTML/Rich Text Format for Composing 

While Outlook typically defaults to HTML, please ensure your messages are composed using HTML or Rich Text Format rather than plain text. This helps preserve formatting and encoding compatibility. You can usually confirm this under the "Format Text" tab when composing an email in Outlook Desktop. 

Microsoft has documented similar issues involving message encoding—particularly when different character sets are involved during sending. While the specific example mentions Chinese characters in the BCC field, the root cause is similar: Email message body is garbled when simplified Chinese characters are included on BCC line 

If the issue continues after trying these steps, we’d recommend reaching out directly to Microsoft Support for further investigation. Since this involves how Outlook internally handles draft encoding, they may be able to look deeper or provide a fix in future updates. You can contact Microsoft Support here: Contact Us - Microsoft Support 

Please feel free to let us know if you’d like help with any of the steps above — we’re more than happy to walk through them with you or assist in any way we can. 

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