"Invalid base64 string for MIME content." error in Mail

Hi All,

I recently set up two mail rules:

1. Move emails that are from my contacts or previous recipients to the “All Inbox” folder.

2. Move emails not in my contacts or previous recipients to the “All Junk Mail” folder.

Since setting these up, I’ve been encountering the following error: “Invalid base64 string for MIME content.” 

It seems to be triggered by these rules, but I’m unsure how to resolve it.

Details:

• Platform: macOS Sequoia

• Mail Client: Apple Mail

• Email Accounts: iCloud, Gmail, and Outlook (Exchange)

Could anyone suggest how to fix this issue or refine the rules to prevent the error?

I appreciate your assistance!

Regards,

Yvan