Alert manager unable to send unsecured emails

[orlmar]

We just upgraded Alertmanager from version 0.9.1 to 0.13.0 and Prometheus from 1.8.1 to 2.1. The Alertmanager's email receiver doesn't work anymore with identical configuration.

In the log, we have an error:
msg="Notify attempt failed" attempt=10 integration=email err="*smtp.plainAuth failed: unencrypted connection"

Could it be related to this issue in net/smtp?
golang/go#22166

Th smtp related configuration is:

global:
smtp_smarthost: 'smtpserver:25'
smtp_from: 'user@domain'
smtp_auth_username: 'user'
smtp_requiere_tls: false
...
receivers:

• name: 'emailreceiver'
  email_configs:
  • to: 'user@domain'
    headers:
    subject: 'testing'
    html: 'some body'

Also we tested requiere_tls parameter in email_configs section for the case it doesn't read the global parameter.

[stuartnelson3]

The issue you linked says the fix for that regression was added to go1.9.2, which was used to compile v0.13.0.

[justlooks]

i have same problem

# ../bin/alertmanager --version
alertmanager, version 0.14.0 (branch: HEAD, revision: 30af4d051b37ce817ea7e35b56c57a0e2ec9dbb0)
  build user:       root@37b6a49ebba9
  build date:       20180213-08:16:42
  go version:       go1.9.2

[CadenOf]

level=error ts=2018-05-23T16:22:43.848809749Z caller=dispatch.go:266 component=dispatcher msg="Notify forr="*smtp.plainAuth failed: unencrypted connection"

I have the same....

Dose anyone know how to fix this problem?

Alertmanager.yml

global:
smtp_smarthost: '.........com:25'
smtp_from: '.............'
smtp_auth_username: '...........'
smtp_auth_password: '..........'
smtp_require_tls: false

@brian-brazil , we need your help

[note]

I also had this problem. This issue (golang/go#22166) suggest that it has been fixed in Go 1.10.x although I doubt it. I ran dockerized alertmanager 0.15.0-rc.3 which is built with go1.10.3 and I still have the same problem.

According to AcalephStorage/consul-alerts#208 Go SMTP lib does not support non-TLS connection against non-local servers.

[simonpasquier]

As stated in the SMTP godoc, the library will allow plain authentication only if TLS is used or the server is local. So you'll have to fulfill one of the conditions to make it work. I'm afraid there's nothing much that can be done on the AlertManager's side.

[note]

@simonpasquier That's understandable then but I would say that it would be nice to have it stated in the alertmanager's docs. If the application exposes smtp_require_tls and the documentation does not states that it's not effective (outside of localhost) then it's quite confusing for the user.

[rschmitz87]

Bump. Running into the same issue, need answers.

[xkfen]

just change the global.smtp_require_tls from false to true