Unable send email to following server: office365.com: 25

Web Testing
1

Hi Team,

I am unable to send the reports after making the email configurations, about 1 years ago, it works, after click Send Test Email button, can send the test email successfully, but it is not working now, after click the ‘send test email’ button , getting a configuration error, see the attached pic below..

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2

@garenliu01 : Can you try with port : 587

3

Yes, i also tied 587, get same issue

4

use the below as host and check

smtp-mail.outlook.com

5

@garenliu01 : did it work?

6

hi @garenliu01

“worked a year ago, same settings fail now” with office 365 is almost always microsoft, not katalon. katalon’s email report uses plain smtp auth (username + password), and exchange online has been switching that off: security defaults block it, and tenants where it was still on are being disabled in waves through 2025.

things to check, in this order:

  1. host smtp.office365.com, port 587, “secure protocol” TLS. port 25 is relay only and will not accept a login.
  2. ask your admin to enable “authenticated smtp” for that one mailbox (exchange admin center > mailbox > manage email apps). if the tenant has security defaults on, that switch alone is not enough, they need to allow it there too.
  3. if the account has mfa, the normal password will never work, you need an app password or a mailbox without mfa dedicated to reports.

if the admin will not open smtp auth, the fallback that worked for me is to send through an internal relay or a service like sendgrid instead, katalon only needs an smtp host that accepts the login.

7

Hi @garenliu01,

Port 25 on Office 365 is for relay only, so it won’t accept a username and password login. For authenticated sending, try:

  • Host: smtp.office365.com
  • Port: 587
  • Secure protocol: TLS (STARTTLS)
  • Username: the full mailbox address

If that still fails, it is usually Microsoft’s tenant security rather than Katalon:

  1. SMTP AUTH may be disabled. Your Exchange admin can enable “Authenticated SMTP” for that mailbox (Exchange admin center > Mailbox > Manage email apps), and also allow it if security defaults are on.
  2. MFA accounts. A normal password won’t work for SMTP on an MFA-enabled account. Use a dedicated mailbox for reports.
  3. Basic auth is being phased out. Microsoft plans to disable Basic auth for SMTP AUTH by default for existing tenants at the end of December 2026. Even if it works today, it may stop soon.

The alternative is to skip that dialog and send the report yourself from a custom keyword which I have been using since long time back, just you need to follow the below points, and easily can send, receive or read mail

  • Register an app in Azure (Entra ID).
  • Grant it the Mail.Send application permission and give admin consent.
  • Authenticate with the client ID, tenant ID and client secret.
  • Call Microsoft Graph’s sendMail endpoint from Groovy.

The above alternative method is the best way