TopicIT Networking →
⌚ About 2 min read
backover the SMTP server to use to send emails from an application.
Avant de commencer : adaptez toujours les commandes et manipulations à votre environnement. Sur un système de production, prévoyez une backup ou un retour arrière lorsque l’action peut modifier la configuration.
Étapes à suivre
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1
Identify the courier provider
Determine if the box is hosted by Microsoft 365, Google Workspace, Infomaniak, OVHcloud or another provider.
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2
View supplier documentation
Remove the SMTP name, port, encryption type and of authentication mode.
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3
Do not confuse MX and SMTP client
The MX server for receiving is not necessarily the SMTP server for submitting.
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4
Test Connectivity
Then test the port with Test-Net Regina.
Commands utiles
Test-Net Gonnement smtp.example.fr -Port 587
À retenir
- Port 587 with ▼TLS is commonly used for authenticated submission.
- Some platforms disable the default standard SMTP authentication.
SMTP: distinguish authentication, envelope and visible identity
Technical checkpoints
- The authenticated SMTP user, MAIL FROM and From: header can be three different identities.
- A Send As / sender mismatch error occurs when the server accepts authentication but rejects the requested sender identity.
- Message-ID, Return-Path and Received headers help reconstruct the actual message path.
Reading a failure
Keep the full SMTP response code and compare authenticated account, envelope sender and visible From.
AUTH user@example.com
MAIL FROM:<sender@example.com>
From: Display <sender@example.com>