Mail Notification Error

Hello All,

I have started getting this error when i want to update any order status. I have contacted my hosting company, they checked email server and replied everything is working fine.

ErrorSMTP Error: Data not accepted.

ErrorMessage could not be sent.

Mailer Error: SMTP Error: Data not accepted.

SMTP server error:

Also my web mail is working fine and i can send email from my Iphone with same email account.

I have checked all email settings from my admin, they are also OK.

I have never experienced this error and my website has been running more than 1 year.

How can identify the problem and solve it.


ErrorSMTP Error: Data not accepted.

ErrorMessage could not be sent.

Mailer Error: SMTP Error: Data not accepted.

SMTP server error:


possibly you have installed 3rd-party modules recently and one of them causes the issue

if it is possible, please try to disable these modules one-by-one and test order status change.

also do other email notifications work properly? e.g. registration of new user?

best regards,

WSA team


Thank you for your reply.

I just disabled a add on i installed long time ago tried but got same error again.

Yes, actually SMTP error occurs for new customer registration too. There was no change / edit with my software before this error. I suppose it is because of email server however hosting team checked mail server logs and there is nothing unusual.

Can it be a wrong port?

Did you try setting up the same account on Thunderbird to see if it works?


Is there any port field in Cs-Cart admin panel. I am using it from my iphone and it works fine.


I'm having a similar issue,

We use amazon SES system, the identical settings work for another domain on 4.1.4

However on a 4.3.1 website we are getting the error “[color=#444444][font=customFont, Arial, sans-serif][size=5]SMTP Error: Data not accepted.”[/size][/font][/color]

This is only on order changes, and not on user updates or other emails etc, ( all non order mails deliver correctly)

Anyone else with this issue? OR how to correct it?


hi [color=#282828][font=arial, verdana, tahoma, sans-serif]Stephen,[/font][/color]

[color=#282828][font=arial, verdana, tahoma, sans-serif]please contact your server admin and ask to check error logs[/font][/color]

[color=#282828][font=arial, verdana, tahoma, sans-serif]best regards,[/font][/color]

[color=#282828][font=arial, verdana, tahoma, sans-serif]WSA team[/font][/color]


[SOLVED] ! Details here:

To resolve the issue " Mailer Error: SMTP Error: Data not accepted. ",

Check all connection settings to be set properly:



Pass: secretpassword

Use Encrypted Connection: TLS

SMTP Authentification: Checked

Make sure that the user "" set above has the "Send As" permissions set (in Office365 administration panel), for the store administrations email account set in "CS-Cart > Settings > Company" .

For example: should be allowed to send emails from in Office365 exchange settings.

Set : "via PHP mail function" as "Method of sending e-mails:"

Hi guys i have the same problem,

sending transactional email with Zoho, but my form give me same error:
Mailer Error: SMTP Error: Data not accepted

And even form I want to send with zoho,

what i need to fix?