🐛 [Bug] Backend – If one Sends Really a lot of Mentions in a Post the Backend Throws an Error

[Tirokk]

🐛 Bugreport

Backend – If a user puts a lot of mentions in a post/comment the backend throws an error (see below) and no notifactions are sent.

• duplicate of #2656

Additional Information

An error on the backend of wir.social:

yarn run v1.22.19
$ node dist/
Warning: Sentry middleware inactive.
🚀 Server ready at http://localhost:4000/
🚀 Subscriptions ready at ws://localhost:4000/graphql
/app/node_modules/nodemailer/lib/smtp-connection/index.js:1199
            this._onError(new Error('Invalid greeting. response=' + str), 'EPROTOCOL', str, 'CONN');
                          ^

Error: Invalid greeting. response=421 4.7.0 mail.webcraft-media.de Error: too many connections from 164.92.142.135: 421 4.7.0 mail.webcraft-media.de Error: too many connections from 164.92.142.135
    at SMTPConnection._actionGreeting (/app/node_modules/nodemailer/lib/smtp-connection/index.js:1199:27)
    at SMTPConnection._processResponse (/app/node_modules/nodemailer/lib/smtp-connection/index.js:942:20)
    at SMTPConnection._onData (/app/node_modules/nodemailer/lib/smtp-connection/index.js:749:14)
    at SMTPConnection._onSocketData (/app/node_modules/nodemailer/lib/smtp-connection/index.js:195:44)
    at TLSSocket.emit (node:events:513:28)
    at TLSSocket.emit (node:domain:489:12)
    at addChunk (node:internal/streams/readable:324:12)
    at readableAddChunk (node:internal/streams/readable:297:9)
    at Readable.push (node:internal/streams/readable:234:10)
    at TLSWrap.onStreamRead (node:internal/stream_base_commons:190:23) {
  code: 'EPROTOCOL',
  response: '421 4.7.0 mail.webcraft-media.de Error: too many connections from 164.92.142.135',
  responseCode: 421,
  command: 'CONN'
}

Node.js v19.9.0
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

Solution

It seems that the nodemailer has to many connections in parallel at one time and that there are limits on the other side on the e-mail server. And that limit seems different by server. It's the simultaneous login limit, possibly.

Possibilities:

• do bulk sending: login once and send all
  • in general: https://nodemailer.com/smtp/
  • pooled SMTP: https://nodemailer.com/smtp/pooled/
• can the nodemailer buffer the e-mails and send them one by one?
• send the notification e-mails by the backend themself one by one and not in parallel?
• establish a cron job for the notification e-mails?
• for users: Limit the number of mentions per post/comment in the UI. Display an error message if exceeding.

Tasks

• [ ] Update user guide if issue solved (here and here)

Issues and PRs

• related #6593 and #6633

[Tirokk]

Error log just today on yunite.me:

yarn run v1.22.19
$ node build/src/
Warning: Sentry middleware inactive.
🚀 Server ready at http://localhost:4000/
🚀 Subscriptions ready at ws://localhost:4000/graphql
(node:27) NOTE: We are formalizing our plans to enter AWS SDK for JavaScript (v2) into maintenance mode in 2023.
Please migrate your code to use AWS SDK for JavaScript (v3).
For more information, check the migration guide at https://a.co/7PzMCcy
(Use `node --trace-warnings ...` to show where the warning was created)
/app/node_modules/nodemailer/lib/smtp-connection/index.js:1199
            this._onError(new Error('Invalid greeting. response=' + str), 'EPROTOCOL', str, 'CONN');
                          ^
Error: Invalid greeting. response=421-4.7.0 Error: too many connections
421 4.7.0 please see https://kasserver.com/rbl/: 421-4.7.0 Error: too many connections
421 4.7.0 please see https://kasserver.com/rbl/
    at SMTPConnection._actionGreeting (/app/node_modules/nodemailer/lib/smtp-connection/index.js:1199:27)
    at SMTPConnection._processResponse (/app/node_modules/nodemailer/lib/smtp-connection/index.js:942:20)
    at SMTPConnection._onData (/app/node_modules/nodemailer/lib/smtp-connection/index.js:749:14)
    at SMTPConnection._onSocketData (/app/node_modules/nodemailer/lib/smtp-connection/index.js:195:44)
    at Socket.emit (node:events:511:28)
    at Socket.emit (node:domain:489:12)
    at addChunk (node:internal/streams/readable:332:12)
    at readableAddChunk (node:internal/streams/readable:305:9)
    at Readable.push (node:internal/streams/readable:242:10)
    at TCP.onStreamRead (node:internal/stream_base_commons:190:23) {
  code: 'EPROTOCOL',
  response: '421-4.7.0 Error: too many connections\n' +
    '421 4.7.0 please see https://kasserver.com/rbl/',
  responseCode: 421,
  command: 'CONN'
}
Node.js v20.2.0
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.