SMTP random authentication error

[Ouack23]

Hello, thank you for developing this app, which is a complete need for many people :)

Describe the bug

I have people telling me that they cannot login using the magic link received by email. The symptom is that they never get the email, but this it random : sometimes it works, sometimes it doesn't, and not everyone seem to be affected in the same way : some users told me that it didn't work sometimes, other did not so I assume everything is working for them 🤷

Server side, I have this exception :

https://next-auth.js.org/errors#signin_email_error Failed to send email {
  error: {
    message: 'Failed to send email',
    stack: 'Error: Failed to send email\n' +
      '    at Object.sendVerificationRequest (/app/.next/server/chunks/337.js:1:2727)\n' +
      '    at async Promise.all (index 0)\n' +
      '    at async email (/app/node_modules/.pnpm/next-auth@4.24.11_next@15.3.3_@babel+core@7.28.3_react-dom@19.1.0_react@19.1.0__react@1_fd46916a6ab5665cd509e57629bddcfd/node_modules/next-auth/core/lib/email/signin.js:27:3)\n' +
      '    at async Object.signin (/app/node_modules/.pnpm/next-auth@4.24.11_next@15.3.3_@babel+core@7.28.3_react-dom@19.1.0_react@19.1.0__react@1_fd46916a6ab5665cd509e57629bddcfd/node_modules/next-auth/core/routes/signin.js:102:24)\n' +
      '    at async AuthHandler (/app/node_modules/.pnpm/next-auth@4.24.11_next@15.3.3_@babel+core@7.28.3_react-dom@19.1.0_react@19.1.0__react@1_fd46916a6ab5665cd509e57629bddcfd/node_modules/next-auth/core/index.js:221:26)\n' +
      '    at async NextAuthApiHandler (/app/node_modules/.pnpm/next-auth@4.24.11_next@15.3.3_@babel+core@7.28.3_react-dom@19.1.0_react@19.1.0__react@1_fd46916a6ab5665cd509e57629bddcfd/node_modules/next-auth/next/index.js:18:19)\n' +
      '    at async NextAuth._args$ (/app/node_modules/.pnpm/next-auth@4.24.11_next@15.3.3_@babel+core@7.28.3_react-dom@19.1.0_react@19.1.0__react@1_fd46916a6ab5665cd509e57629bddcfd/node_modules/next-auth/next/index.js:91:14)\n' +
      '    at async X (/app/node_modules/.pnpm/next@15.3.3_@babel+core@7.28.3_react-dom@19.1.0_react@19.1.0__react@19.1.0/node_modules/next/dist/compiled/next-server/pages-api.runtime.prod.js:20:18441)\n' +
      '    at async z.render (/app/node_modules/.pnpm/next@15.3.3_@babel+core@7.28.3_react-dom@19.1.0_react@19.1.0__react@19.1.0/node_modules/next/dist/compiled/next-server/pages-api.runtime.prod.js:20:19237)\n' +
      '    at async NextNodeServer.runApi (/app/node_modules/.pnpm/next@15.3.3_@babel+core@7.28.3_react-dom@19.1.0_react@19.1.0__react@19.1.0/node_modules/next/dist/server/next-server.js:676:9)',
    name: 'Error'
  },
  providerId: 'email',
  message: 'Failed to send email'
}
Error sending email [Error: Greeting never received] { code: 'ETIMEDOUT', command: 'CONN' }
Message:  Error sending email: error.message: Greeting never received
error.stack: Error: Greeting never received
    at SMTPConnection._formatError (/app/node_modules/.pnpm/nodemailer@6.10.1/node_modules/nodemailer/lib/smtp-connection/index.js:809:19)
    at SMTPConnection._onError (/app/node_modules/.pnpm/nodemailer@6.10.1/node_modules/nodemailer/lib/smtp-connection/index.js:795:20)
    at Timeout.<anonymous> (/app/node_modules/.pnpm/nodemailer@6.10.1/node_modules/nodemailer/lib/smtp-connection/index.js:729:22)
    at listOnTimeout (node:internal/timers:588:17)
    at process.processTimers (node:internal/timers:523:7)

I noticed this directly after a user told me he didn't receive the link. But, as there is not timestamp on the log, I am not sure that it was output at the same time my user had this problem. I'll try to replicate this with him while watching the log output, to see if anything happens. I'll respond to this issue with any details I get.

We are using the SMTP server from our organization email address, on many self-hosted services and it works well for other apps. He also tried to send an email to himself using said email address and he received the test email without any problem.

To Reproduce

I am using split-pro 1.5.6 docker image and a Postgres 17.6 database in a docker-compose.yml

Fill SMTP creds variables. My SMTP server port is 587, if this can give you any hint.

Expected behavior

User should receive magic links every time they require one.

Screenshots

N/A

App version

1.5.6

Desktop (please complete the following information):

Smartphone (please complete the following information):

N/A

Additional context

Thank you for reading,
Regards

[krokosik]

@Ouack23 I'm glad you enjoy the app :)

You can append timestamps to logs with a flag like docker logs --timestamps

Your issue seems to be specific to your configuration, I've seen this popup when the receiver expects a secure connection. Could you try using the 465 port? If that doesn't help could you share more details about your provider?

[Ouack23]

Thank you for your answer :)

I saw that port 465 is supported in my provider wiki page, I set up this port instead and verified that I was able to log in myself.

I'll get feedback from my users, I'll let you know.

So, this is a problem of STARTTLS not being supported by split-pro ? So how could it work sometimes ? 🤔 I'm not very familiar with such email shenanigans.

[krokosik]

Me neither, I just googled the error message with reference to nodemailer

We automatically set secure to true if the port is set to 465 so hopefully this will work fine. Otherwise, I recommend you just run a minimal nodemailer script on your own and try to find a config that works for you and I'll update the SP config accordingly.