Proton + Emby SMTP Issue

[anuradhaonline 1]

Hi,

I'm having this SMTP error when I'm trying to use Proton Mail to send email notifications similar to below issue. 

"Mailbox name not allowed. The server response was: 5.7.1 : Sender address rejected: not logged in"

https://emby.media/community/index.php?/topic/143790-issue-configuring-proton-smtp-in-emby/

I contacted Proton support and they sent me the following.

The surprising thing is these same details work in Tautulli. It can send out email notifications using Proton SMTP without any issues.

I'm on latest Emby version.

Your help in this matter is highly appreciated.

Thank you.

Edited December 18, 2025 by anuradhaonline
Added the error message

[Luke 42077]

Hi, please follow along here: 

Thanks.

 

[anuradhaonline 1]

Hi Luke,

Thank you for the reply. But, I do not understand the response marked as the solution in this link. Is that related to Windows?

I have hosted Emby on Linux.

Why is it that Tautulli can send out emails but not Emby?

[Luke 42077]

We use a dotnet function to send emails, and I think it has an issue that is preventing it from working with Proton. The details are in the topic. 

[anuradhaonline 1]

Oh.. that makes sense. After doing a Google Search, users have pointed out that there are known issues with contemporary SSL/TLS protocols and authentication mechanisms and have suggested to use MailKit instead.

https://www.reddit.com/r/dotnet/comments/18z95jg/are_you_using_dotnet_builin_mail_or_3rd_part/

https://stackoverflow.com/questions/56010524/protonmail-smtp-bridge-authentication-failed

https://www.reddit.com/r/ProtonMail/comments/1badhub/c_net_asp_and_protonmail_smtp/

Do you know if Emby can use MailKit as well?

[anuradhaonline 1]

@LukeI found this old thread where Anthony was developing another version of Email Notifications. He had used MailKit in there but I don't know how to install that version.

https://emby.media/community/index.php?/topic/84782-email-notifications/

Github Repo

https://github.com/AnthonyMusgrove/email-notifications/

 

 

[Luke 42077]

Hi, yes it’s something to look into. Thanks.