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How to use SMTP in MSG91

A Simple Mail Transfer Protocol (SMTP) is a form of communication between servers used to send and receive email.  


1. Log in to the MSG91 Dashboard and go to the Email service.



2. Go to the Domains settings section from the sidebar. Click on the verified domain on which you wish to enable SMTP. Enable the SMPT toggle. Open the SMTP tool and enter the SMTP hostname, username, Port, and password as given in the Domains section. Make sure you are using the authentication option.



Note- If you are using an online tool, make sure to change the password every time you use a 3rd party tool to send email via SMTP or your domain might get blocked if we think we are receiving spam from your domain..


The emails can only be sent from the verified domain/subdomain on MSG91. Once the mail is sent, you can see the logs in the Logs section. They would show the Type as SMTP.



Errors and Error codes that you might get : 


  1. 535 - 

    1. SMTP Service Disabled by Admin. - Admin has the right to disable SMTP Service for users sending a lot of spam mails.

    2. SMTP Service Disabled by User. - Admin has the right to disable SMTP Service for users sending a lot of spam mails.

    3. The domain xyz.com is not enabled. Please Contact Support.- Domain is disabled due to some reason.

    4. The domain is not verified. SPF, DKIM values must be set and verified on domain DNS records. - SPF, DKIM Records are not verified for the corresponding domain.

    5. Invalid Credentials - Credentials entered by the User are not valid, either invalid username or invalid password.

    6. You do not have sufficient balance for this operation. - There is not enough balance left in User’s account to send emails.

  2. 550 - 

    1. Invalid Mail From address received - User is sending Invalid MAIL FROM Command.

    2. File extension can be one of the following types: (list of supported attachments). - Invalid Attachment has been sent by the User in DATA Command.

    3. Subject cannot contain inappropriate words - Subject contains words which are listed as inappropriate by us.

    4. Body cannot contain inappropriate words - Body contains words which are listed as inappropriate by us.

    5. Cannot Connect to Server, Please try again after some time. - Some issue has occurred at the mailer server and needs to be fixed.

    For IP security features for SMTP service please refer to this article : https://msg91.com/help/transactional-email/IP-Security-Feature-in-SMTP-services?version=V1