Quick troubleshooting view
SMTP server accepts the authentication but refuses data with a message Sender mismatch because the sender does not match the account or an authorized alias.
- From different from SMTP account
- WordPress plugin using another address
- Is not authorised
- Identify SMTP account
- Compare From
- Control the alias
- align the From address with the SMTP account
- use an explicitly authorised alias
- fix the configuration of the SMTP plugin
Contextual technician plan
Remove the address used for authentication.
“Identify SMTP account” should produce an observation that clearly confirms or rules out “From different from SMTP account”.
If the observation is normal, lower “From different from SMTP account” in the ranking and continue with the next distinct check.
If the observation is abnormal, keep the evidence and investigate “From different from SMTP account” first. Related action: align the From address with the SMTP account.
Check the address actually used by the application.
“Compare From” should produce an observation that clearly confirms or rules out “WordPress plugin using another address”.
If the observation is normal, lower “WordPress plugin using another address” in the ranking and continue with the next distinct check.
If the observation is abnormal, keep the evidence and investigate “WordPress plugin using another address” first. Related action: use an explicitly authorised alias.
Be sure that the sender is allowed on the host side.
“Control the alias” should produce an observation that clearly confirms or rules out “Is not authorised”.
If the observation is normal, lower “Is not authorised” in the ranking and continue with the next distinct check.
If the observation is abnormal, keep the evidence and investigate “Is not authorised” first. Related action: fix the configuration of the SMTP plugin.
Do a test with the same From as the SMTP account.
“Test with the exact address” should produce an observation that clearly confirms or rules out “Return-Path or inconsistent SMTP envelope”.
If the observation is normal, lower “Return-Path or inconsistent SMTP envelope” in the ranking and continue with the next distinct check.
If the observation is abnormal, keep the evidence and investigate “Return-Path or inconsistent SMTP envelope” first. Related action: avoid forcing an arbitrary sender.
Repeat the same validation test after the correction and confirm the original symptom is gone. Validate stability before closing the incident.
Before changing configuration, record the current value and a way back.
Escalader if the same account and the same From are used but the server continues to return Sender mismatch.
SMTP server accepts the authentication but refuses data with a message Sender mismatch because the sender does not match the account or an authorized alias.
Causes probables
- From different from SMTP account
- WordPress plugin using another address
- Is not authorised
- Return-Path or inconsistent SMTP envelope
Diagnostic étape par étape
- 1
Identify SMTP account
Remove the address used for authentication.
- 2
Compare From
Check the address actually used by the application.
- 3
Control the alias
Be sure that the sender is allowed on the host side.
- 4
Test with the exact address
Do a test with the same From as the SMTP account.
Solutions possibles
- align the From address with the SMTP account
- use an explicitly authorised alias
- fix the configuration of the SMTP plugin
- avoid forcing an arbitrary sender
Escalader if the same account and the same From are used but the server continues to return Sender mismatch.