I looked around similar old posts but couldn’t find any solution. How do we solve this?
I have entered correct Microsoft credentials
SMTP Host: smtp.office365.com
SMTP Username: myusername@domain.com
SMTP Password: my password
Use encrypted connection: TLS
Mail only works when I use “via PHP Mail Function” but I dont want to use this. Also I have enabled SMTP authentication on Microsoft.
- Checking the “TLS” and saving wont work as I get his error,
" SMTP Error Password command failed: 535 5.7.3 Authentication unsuccessful [SJ0PR05CA0147.namprd05.prod.outlook.com 2023-05-15T21:24:44.445Z 08DB54B25FF6F4F1]"
- Mail notifications get this error, " Error Message could not be sent.
Mailer Error: The following From address failed: email@domain.com : MAIL FROM command failed,Client not authenticated to send mail. [SJ0PR03CA0138.namprd03.prod.outlook.com 2023-05-15T21:39:57.751Z 08DB548C6600C450] ,530,5.7.57SMTP server error: MAIL FROM command failed Detail: Client not authenticated to send mail. [SJ0PR03CA0138.namprd03.prod.outlook.com 2023-05-15T21:39:57.751Z 08DB548C6600C450] SMTP code: 530 Additional SMTP info: 5.7.57SMTP server error: MAIL FROM command failed Detail: Client not authenticated to send mail. [SJ0PR03CA0138.namprd03.prod.outlook.com 2023-05-15T21:39:57.751Z 08DB548C6600C450] SMTP code: 530 Additional SMTP info: 5.7.57
This is frustrating as I have been doing research on this for hours but no solution.
I assume that " myusername@domain.com" and “email@domain.com” are replaced in your store with proper e-mail addresses? 
Try setting host to smtp.office365.com:587
Yes those are replaced with proper email, I just didn’t want to disclose too much.
I will try your suggestion and see what happens.
Thanks for your reply.
I tried your suggestion but it failed and returned the same errors. I couldn’t save the checked TLS and mail couldn’t be sent.
Hello
Did you try with SSL and smtp.office365.com:465
Best regards
Robert
If you are using CS-Cart Multi-Vendor I can assume that the error
The following From address failed: email@domain.com : MAIL FROM command failed,Client not authenticated to send mail
can be fixed by enabling the Send vendor emails from marketplace email addresses setting at the Settings > E-mails, this will however, change the email address of the sender, but anyway it is better than not sending emails at all 
As for the authentication error, I would suggest that you check the Microsoft documentation for the correct SMTP settings, or even contact their support for assistance.
No I am not suing multivendor. As for contacting Microsoft, I did that and yet to receive feedback, besides their SMTP setup are already on their website as well as on countless other articles on the internet. So not sure what Microsoft will do differently.
Have tried the suggestion by @soft-solid and I got this error SMTP Error Failed to connect to server: Connection timed out (110)
Hello
Please prepare screenshot from your configuration email in shop
Are you sure that password is correctly?
Best regards
Robert
If this is not Multi-Vendor, please ensure that all the email addresses specified in the Settings > Company page match the username specified in the SMTP settings, e.g. myusername@domain.com.
I used different shared mailboxes such as sales@domain.com , support@domain.com in the company settings. And then in the SMTP I used an actual user mailbox with login capabilities.
It seems that Microsoft mail servers reject emails sent from an email address that is different from the one used to send the email.
So you can either specify the same email address that is used to send notifications or change the method of sending emails. For example, you could try using a different email service for SMTP or switch to php mail.
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