# Outlook classic or modern doesn't work with SMTP Postfix: Modern TLS 1.3 only setting
**URL:** https://forum.yunohost.org/t/outlook-classic-or-modern-doesnt-work-with-smtp-postfix-modern-tls-1-3-only-setting/41773
**Category:** Support
**Tags:** email, mail, english
**Created:** [March 8, 2026, 8:37pm UTC](https://forum.yunohost.org/t/outlook-classic-or-modern-doesnt-work-with-smtp-postfix-modern-tls-1-3-only-setting/41773 "2026-03-08T20:37:22Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@ajoe04](https://forum.yunohost.org/u/ajoe04)
#### Post date: [March 8, 2026, 8:37pm UTC](https://forum.yunohost.org/t/outlook-classic-or-modern-doesnt-work-with-smtp-postfix-modern-tls-1-3-only-setting/41773/1 "2026-03-08T20:37:22Z")
**What type of hardware are you using** : Virtual machine
**What YunoHost version are you running** : 12.1.39 and 13.0.4
**How are you able to access your server** : The webadmin
**Are you in a special context or did you perform specific tweaking on your YunoHost instance ?** : no
### Describe your issue
Connecting Outlook Mail Client with Yunohost doesn’t work with “Modern (TLS 1.3 only)”.
If you set the Postfix-Compatibility setting to: “Modern (TLS 1.3 only)” it doesn’t work with Outlook.
You find it here: HOSTNAME/yunohost/admin/#/tools/settings/security
Solution:
Use “Intermediate (allows TLS 1.2)” as the security setting of postfix SMTP.
### Share relevant logs or error messages
no need. I also provided the solution. Just for others to help them.
---
### Author:  [@orhtej2](https://forum.yunohost.org/u/orhtej2)
#### Post date: [March 8, 2026, 9:03pm UTC](https://forum.yunohost.org/t/outlook-classic-or-modern-doesnt-work-with-smtp-postfix-modern-tls-1-3-only-setting/41773/2 "2026-03-08T21:03:26Z")
It does not (as in - you’ve tried and it did not work) or the string claims so (as in the description is outdated)?
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### Author:  [@williamswelsh](https://forum.yunohost.org/u/williamswelsh)
#### Post date: [March 9, 2026, 6:11am UTC](https://forum.yunohost.org/t/outlook-classic-or-modern-doesnt-work-with-smtp-postfix-modern-tls-1-3-only-setting/41773/3 "2026-03-09T06:11:55Z")
Thanks for sharing this! Confirmed — Outlook doesn’t support TLS 1.3 only. Switching Postfix to “Intermediate” mode resolves the SMTP connection issue perfectly.
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### Author:  [@ajoe04](https://forum.yunohost.org/u/ajoe04)
#### Post date: [March 9, 2026, 8:48am UTC](https://forum.yunohost.org/t/outlook-classic-or-modern-doesnt-work-with-smtp-postfix-modern-tls-1-3-only-setting/41773/4 "2026-03-09T08:48:33Z")
I did the following tests with “Modern (TLS 1.3. only)” active for postfix SMTP server:
1. Outlook Classic Window 11 latest update → Yunohost 12.1.39 or 13.0.4 → doesn’t work.
2. Outlook Modern Apple MacOS Version 26.3.1 → Yunohost 12.1.39 or 13.0.4 → doesn’t work.
→ Outlook reports an error with the SMTP connection.
3. With Thunderbird version 148.0 it works on both operating systems fine.
I did the following tests with “Intermediate (allows TLS 1.2)” active:
1. Outlook Classic Window 11 latest update → Yunohost 12.1.39 or 13.0.4 → It works!
2. Outlook Modern Apple MacOS Version 26.3.1 → Yunohost 12.1.39 or 13.0.4 → It works!
3. With Thunderbird version 148.0 it works on both operating systems fine.
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### Author:  [@ajoe04](https://forum.yunohost.org/u/ajoe04)
#### Post date: [March 9, 2026, 8:50am UTC](https://forum.yunohost.org/t/outlook-classic-or-modern-doesnt-work-with-smtp-postfix-modern-tls-1-3-only-setting/41773/5 "2026-03-09T08:50:46Z")
This information is missing on this page:
> **[Configure email clients | Yunohost](https://doc.yunohost.org/en/admin/email/clients/)**
>
> You can fetch and send emails using your YunoHost instance from desktop email clients such as Thunderbird Desktop or on your smartphone with applications like K-9 Mail.
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### Author:  [@orhtej2](https://forum.yunohost.org/u/orhtej2)
#### Post date: [March 9, 2026, 9:21am UTC](https://forum.yunohost.org/t/outlook-classic-or-modern-doesnt-work-with-smtp-postfix-modern-tls-1-3-only-setting/41773/6 "2026-03-09T09:21:36Z")
By the power of open source the documentation can be update here: [doc/docs/admin/35.email/05.clients.mdx at main · YunoHost/doc · GitHub](https://github.com/YunoHost/doc/blob/main/docs/admin/35.email/05.clients.mdx) 😉
---
### Author:  [@ajoe04](https://forum.yunohost.org/u/ajoe04)
#### Post date: [March 9, 2026, 9:41am UTC](https://forum.yunohost.org/t/outlook-classic-or-modern-doesnt-work-with-smtp-postfix-modern-tls-1-3-only-setting/41773/7 "2026-03-09T09:41:38Z")
> [@orhtej2](#):
>
> doc/docs/admin/35.email/05.clients.mdx at main · YunoHost/doc · GitHub
yes. this is the pull request:
>
>
> Added important notes regarding Microsoft Outlook's TLS 1.3 compatibility and se…curity settings for Postfix.
>
> \## Problem
>
> \- Important Information about Outlook security setting in yunohost are missing.
>
> \## Solution
>
> \- Adding this information to the Outlook Client documentation.
>
> \## PR checklist
>
> \- \[\] PR finished and ready to be reviewed
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### Author:  [@system](https://forum.yunohost.org/u/system)
#### Post date: [April 8, 2026, 9:41am UTC](https://forum.yunohost.org/t/outlook-classic-or-modern-doesnt-work-with-smtp-postfix-modern-tls-1-3-only-setting/41773/8 "2026-04-08T09:41:56Z")
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