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SMTP (basic authentication) suddently doesnt work anymore

  • July 11, 2025
  • 3 comments
  • 253 views
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In the past, we sent the backup logs by e-mail. The settings for sending emails were set under Email Settings --> SMTP server (basic authentication); Port 587; Connect using SSL. Authentication was via credentials. From one day to the next, this dispatch no longer worked. When I now try to save the configuration, I get the message: ‘Unable to connect to SMTP server because of invalid credentials or connection settings’. I tested a Thunderbird on the same device with the same smtp settings and it worked there.

 

Any idea why Veeam can't manage SMTP authentication right now?

Best answer by TechnikHDT

Hey Giovanini,

i found the Problem, the timout must be set to 100,000 ms and then it works. Thanks for your help anyways. 

matheusgiovanini

3 comments

matheusgiovanini
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It’s likely that your SMTP provider (like Microsoft 365 or Gmail) has recently disabled basic authentication (username/password) for security reasons. Even though Thunderbird might still work due to cached sessions or different auth handling, Veeam strictly relies on the configured authentication method.

Veeam Backup & Replication (from version 11a) supports modern authentication (OAuth2) for Microsoft 365 and Gmail, but this support does not yet extend to all Veeam components (like Agents or Remote Console). If you're using one of those, basic auth is still required, which may no longer be accepted by your mail provider.


Configuring Global Email Notification Settings - User Guide for VMware vSphere

 

 

Matheus Giuliano Giovanini | Senior Backup Analyst | Veeam Legend | Blog: techdirectarchive.com
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  • TechnikHDT
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  • July 14, 2025

Hey Giovanini,

i found the Problem, the timout must be set to 100,000 ms and then it works. Thanks for your help anyways. 

Tommy O'Shea
matheusgiovanini
Tommy O'Shea
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  • Tommy O'Shea
  • Veeam Legend
  • July 14, 2025

Hey Giovanini,

i found the Problem, the timout must be set to 100,000 ms and then it works. Thanks for your help anyways. 

Glad you were able to find a solution to your problem. Be sure to select a comment as the “Best Answer”, even if it is your own.

Tommy O’Shea, VMCE, VMCE-SP, VMCA
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