How to resolve 'internationalized email message (SMTPUTF8) not supported' error after upgrading to V3?

When encountering the following error:

internationalized email message (SMTPUTF8) not supported

after upgrading to Nylas V3, this typically indicates a compatibility issue with the email server's UTF-8 settings. The issue can be resolved by:

1. Contacting your email administrator
2. Having them check and potentially disable SMTPUTF8 on the email server

This solution has helped customers successfully resolve NDR (Non-Delivery Report) issues related to UTF-8 encoding after upgrading to V3.

Updated April 09, 2025 17:42