completely SMTPUTF8 + IMAP4rev2 Support (RFC 6531 + RFC 9051)

[Ótzï]

Currently, no EAI email addresses (such as äöü@test.local) can be set up in Thunderbird, whether on a desktop or mobile device. Entering punycode is not a solution either, because EAI (SMTPUTF8) means native UTF-8, and there are no intermediate encodings such as punycode for IDN.

So the request is to support the setup of EAI email addresses with SMTPUTF8 addresses (So non-ASCII characters BEFORE the @).

I hereby request full support for IMAP4rev2 (RFC 9051) and SMTPUTF8 (RFC 6531) in Thunderbird, whether on desktop or mobile.

(The email addresses in the images do not exist, but that doesn't matter because you can't even get to the settings where ports/mail servers etc. are entered).

 

[Misl]

RFCs are more important than some styles

[Linux_Maschine]

Usernames and IDs are in Unicode.

[Voralen]

Full support for SMTPUTF8 and IMAP4rev2 is becoming increasingly important for true internationalization. Beyond supporting non-ASCII email addresses, it would also improve interoperability with modern mail servers and help Thunderbird stay aligned with current IETF standards. This would be a valuable long-term investment in standards compliance and global usability.

[VerniceCollins]

I support this idea. As EAI adoption continues to grow, full SMTPUTF8 and IMAP4rev2 support will become increasingly important for interoperability. Even if these addresses aren't common yet, users should be able to configure and use standards-compliant email accounts without workarounds or encoding limitations. Native UTF-8 support across both desktop and mobile would make Thunderbird more future-proof and aligned with the relevant RFCs.

[Roblo]

Full SMTPUTF8 (RFC 6531) and IMAP4rev2 (RFC 9051) support is not just a "nice to have" feature anymore. Internationalized email addresses are part of modern Internet standards and are becoming increasingly important as more organizations adopt EAI.

From a user's perspective, an email client should simply accept valid email addresses without requiring workarounds or rejecting them during account setup. Lack of support creates unnecessary compatibility issues and makes Thunderbird less attractive in environments where internationalized addresses are already in use.

Implementing these standards would also reinforce Thunderbird's reputation as a standards-compliant, future-proof email client. I hope this can be prioritized.