Mandatory field issue for Email (SMTP) notification

[GomoDD]

📑 I have found these related issues/pull requests

n/a

🛡️ Security Policy

• I have read and agree to Uptime Kuma's Security Policy.

📝 Description

Uptime-Kuma instance: Docker on Ubuntu 22.04
Uptime-Kuma version: Version: 1.23.16

Issue:
"Email (SMTP)" notification cannot be used in combination with SMTP servers / relays which do not require authentication as Uptime-Kuma is treating "Login" (Password*) as a mandatory field.

This leads to "Email (SMTP)" not being usable in local setups where local SMTP mail-relays are setup to not require authentication as they have IP based whitelisting in place.

When notification is triggered, it does not end up getting sent (see docker log).
In addition, when editing / creating "Email (SMTP)" notification (without login / password), it is also not possible to perform a "Test", as that also fails / expects password field to have a value.

See attached screenshots.

👟 Reproduction steps

Create new "Email (SMTP)" notification, fill out all the usual fields but "Login" should be left empty (-> SMTP server does not require password authentication)

👀 Expected behavior

"Email (SMTP)" should attempt to send email even if the "Login" field has not been filled out.

😓 Actual Behavior

"Email (SMTP)" does not attempt to send email if the "Login" field has not been filled out.

🐻 Uptime-Kuma Version

1.23.16

💻 Operating System and Arch

Ubuntu 22.04.5 LTS

🌐 Browser

Google Chrome 140.0.7339.128

🖥️ Deployment Environment

• Runtime Environment:
  • Docker: 28.4.0, build d8eb465

📝 Relevant log output

2025-09-19T10:07:34+02:00 [MONITOR] ERROR: Cannot send notification to UptimeKuma Email Alert
Error: Missing credentials for "LOGIN"
    at SMTPConnection._formatError (/app/node_modules/nodemailer/lib/smtp-connection/index.js:807:19)
    at SMTPConnection.login (/app/node_modules/nodemailer/lib/smtp-connection/index.js:452:38)
    at /app/node_modules/nodemailer/lib/smtp-transport/index.js:272:32
    at SMTPConnection.<anonymous> (/app/node_modules/nodemailer/lib/smtp-connection/index.js:215:17)
    at Object.onceWrapper (node:events:631:28)
    at SMTPConnection.emit (node:events:517:28)
    at SMTPConnection._actionEHLO (/app/node_modules/nodemailer/lib/smtp-connection/index.js:1369:14)
    at SMTPConnection._processResponse (/app/node_modules/nodemailer/lib/smtp-connection/index.js:991:20)
    at SMTPConnection._onData (/app/node_modules/nodemailer/lib/smtp-connection/index.js:772:14)
    at SMTPConnection._onSocketData (/app/node_modules/nodemailer/lib/smtp-connection/index.js:195:44) {
  code: 'EAUTH',
  command: 'API'
}