Error: "Unable to login to SMTP connection" and "Failed to get response to login password" when sending Test e-mail from Company Maintenance

Summary

Errors like "Unable to login to SMTP connection" and "535 Username and Password not accepted" occur in Sage 100 email test. These issues relate to authentication, password limits, and provider security settings.

Description

When you send a test email from Company Maintenance in Sage 100, the system returns errors such as:
  • "Unable to login to SMTP connection"
  • "Failed to get response to login password"
  • "535 Username and Password not accepted"
These errors appear in the Chilkat log and indicate failed SMTP authentication.
Sample ChilKat errors:
  • login_method: LOGIN, 535 Incorrect authentication data, failed to get response to login password   
  • login_method: LOGIN, 535 5.7.3 Authentication unsuccessful, failed to get response to login password     
  • 535 user has been restricted (no detailed error message except 535, this can be due to a wrong email account password on Company Maintenance Email information).  Failed to get response to login password   
  • 535-5.7.8 SMTP Authentication Error "Username and Password not accepted" (535 5.7.8)  
  • SmtpCmdResp: 535-5.7.8 Username and Password not accepted. Learn more at, SmtpCmdResp: 535 5.7.8  https://support.google.com/mail/?p=BadCredentials

2-factor authentication

Sage 100 2021 and higher: Use Oauth to authenticate SMTP email requests.

  • In Sage 100, Library Master, Main menu, Company Maintenance, E-mail tab, select Authentication Method "Oauth" and enter the requisite information.

Sage 100 2020 and before

  1. On versions of Sage 100 2020 and before, with Office 365 multi-factor authentication enabled on an account, authentication will fail via Sage 100 as there is not a way to pass the additional authentication needed. An alternative is to use either another Office 365 account, without multi-factor authentication enabled, or another email configuration without multi-factor authentication enabled (such as client's Gmail, Yahoo mail, etc.) would need to be chosen and configured in Company Maintenance as a workaround.
  2. (from Microsoft) To create app passwords using the Office 365 portal:
  3. Sign in to your work or school account, go to the My Account page, and select Security info.
  4. Select Add method, choose App password from the list, and then select Add.
  5. Enter a name for the app password, and then select Next.

Manage app passwords for two-step verification
https://support.microsoft.com/en-gb/account-billing/manage-app-passwords-for-two-step-verification-d6dc8c6d-4bf7-4851-ad95-6d07799387e9

Multifactor authentication for Microsoft 365
https://docs.microsoft.com/en-us/microsoft-365/admin/security-and-compliance/multi-factor-authentication-microsoft-365?view=o365-worldwide

NOTE:

Security defaults is a feature for Microsoft 365 and Office 365 paid, or trial subscriptions created after October 21, 2019. These subscriptions have security defaults turned on, which:

  1. Requires all of your users to use MFA with the Microsoft Authenticator app.
  2. Blocks legacy authentication

Cause

SMTP login fails when the server doesn’t accept the provided credentials or authentication method.
Common causes include:
  • Multi-factor authentication blocks standard SMTP login
  • Incorrect username or password
  • Password length limitations in older Sage 100 versions (14-character limit)
  • SMTP server security settings or connection limits
  • Legacy authentication blocked by the email provider

Resolution

 CAUTION: This solution requires advanced knowledge of Windows security and network settings. Sage isn't responsible for any issues that arise from changes to these settings. Ensure you back up all system and application databases necessary for a complete restoration. It's advisable to contact a certified consultant or your system administrator for assistance.


CAUTION: This solution needs advanced Operating System knowledge. Consult your system administrator for help. Sage isn't liable for issues caused by improper changes to the Windows Registry. Always back up your data before applying advanced solutions.
CAUTION: Sage support can't assist with third-party products, hardware, report customizations, or state and federal tax questions. Refer to our Scope of Support for more info. Contact your Sage business partner, network administrator, or accountant for assistance.

NOTE:

There are numerous different server programs and providers that provide the services of an SMTP e-mail server. Sage does not test Sage 100 with all e-mail services/programs/providers. Sage 100 Customer Support is not responsible for knowing the exact combination of program or provider, security or permission settings, inbound or outbound rules, account logins, passwords, bandwidth restrictions, etc. to enable successful e-mail delivery. The specifics of services, programs, and providers are subject to change. If an error is encountered, troubleshoot based on the Chilkat error log information. You may need to try various settings, or test an alternate service, program, or provider.

 Possible Resolutions:

Verify login credentials

  • Confirm the username and password in Company Maintenance match the email account.
  • Test login through the provider’s web portal to confirm credentials. 

Review SMTP server logs

  • Enable SMTP logging on the email server.
  • Review handshake attempts and authentication responses.
  • Adjust settings based on log results.

 Check SMTP connection limits

  • Confirm the server allows multiple login attempts.

Check and Verify login credentials

  • Confirm the username and password in Company Maintenance match the email account.
  • Test login through the provider’s web portal to confirm credentials.

Address multi-factor authentication (MFA)

Sage 100 2021 and later

  • Open Library Master, Main menu, Company Maintenance, E-mail tab.
  • Set Authentication Method to Oauth.
  • Enter the required OAuth credentials.

Sage 100 2020 and earlier

  • Use an account without MFA enabled.
  • Or configure an alternative email provider without MFA.

Use app passwords for MFA accounts

  • Sign in to your Microsoft 365 account.
  • Go to Security info, then select Add method.
  • Choose App password and follow prompts.
Use this app password in Sage 100 instead of your regular password.
Refer to:

Enable access for less secure apps (if required)

  • If getting "Username and Password not accepted" 535 5.7.8 error, but the username and password work logging onto email via web (with 2-factor authentication), you may need to enable "Access for less secure apps" (allow exceptions to 2-factor authentication) in your email settings.
  • For Gmail accounts:

CAUTION:

This option reduces account security. Use only when required and temporary.

Understand provider limitations

  • Email providers enforce different authentication rules and restrictions.
  • Sage doesn’t control provider security policies or connection rules.
  • You must adjust settings based on the provider’s requirements.

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Solution Properties

Solution ID
224924650068108
Last Modified Date
Fri Jul 03 01:00:35 UTC 2026
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