Azure App Service
Azure App Service is a service used to create and deploy scalable, mission-critical web apps.
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The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.7.0 Authentication Required
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(278.4, 36%, 36%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EB%3C/text%3E%3C/svg%3E)
BR
21
Reputation points
Emails are not going out from azure / app deployed
Azure App Service
{count} votes
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(12.8, 39%, 11%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ELM%3C/text%3E%3C/svg%3E)
Loknathsatyasaivarma Mahali 1,870 Reputation points Microsoft External Staff Moderator2025-04-29T22:24:22.88+00:00 Hello BR,
Thanks for reaching out, could you please tell us more about the issue also could you please confirm on the below?
- What exactly you are implementing and how, are your referring any document?
- What SMTP server you are using, and encryption method (SSL/TLS) are you using?
- Are you using valid credentials, have you enabled app-specific passwords or allowed less secure apps?
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Loknathsatyasaivarma Mahali 1,870 Reputation points Microsoft External Staff Moderator
2025-04-30T21:49:01.7233333+00:00 Hello BR,
Just checking in to see if you had a chance to review my previous message and provide the necessary details to help us troubleshoot the issue further.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(278.4, 57.99999999999999%, 36%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EJF%3C/text%3E%3C/svg%3E)
John Ferguson 0 Reputation points2025-05-01T18:27:50.3166667+00:00 I just started having the same problem using VB.NET. Code stopped working this morning.
SMTP server is smtp.gmail.com using port 587 with ssl enabled.
username and password has been confirmed and allow less secure apps is enabled
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(112.00000000000001, 77%, 20%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3ES%3C/text%3E%3C/svg%3E)
Sampath 2,845 Reputation points Microsoft External Staff Moderator2025-05-05T05:09:29.96+00:00 Hello @BR,
Based on the provided conversation and error message:
This issue is typically caused by changes in SMTP server authentication requirements or misconfiguration. Given you're using
smtp.gmail.comwith port587and SSL/TLS enabled, and Gmail is tightening security protocols, here's a detailed explanation and solution path:You need to switch to OAuth 2.0 or use an App Password if 2-Step Verification is enabled.
Step to Fix Using App Password :
- Enable 2-Step Verification on your Google account.
- Under “Signing in to Google”, enable 2-Step Verification.
- Once enabled, go to “App Passwords”.
- Generate a new password for “Mail” and your app (e.g., ".NET App").
- Use this App Password in your SMTP configuration instead of your usual Gmail password.
Sample VB .NET SMTP Configuration
Dim smtpClient As New SmtpClient("smtp.gmail.com", 587) smtpClient.EnableSsl = True smtpClient.Credentials = New NetworkCredential("******@gmail.com", "your-app-password") Dim mailMessage As New MailMessage() mailMessage.From = New MailAddress("******@gmail.com") mailMessage.To.Add("recipient@example.com") mailMessage.Subject = "Test Email" mailMessage.Body = "This is a test email sent from VB.NET" smtpClient.Send(mailMessage)If you're hosting in Azure, consider using a more secure SMTP relay like:
- SendGrid (free tier available in Azure)
- Microsoft 365 Exchange SMTP relay
This avoids Google security restrictions and is better suited for production.
- Try generating and using an App Password.
- If issues persist, switch to a dedicated SMTP provider like SendGrid via Azure Marketplace.
Let me know if you have any further assistances in comments.
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(195.2, 39%, 28%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EJF%3C/text%3E%3C/svg%3E)
John Ferguson 0 Reputation points2025-05-05T06:01:33.33+00:00 No, that didn't work either. The problem appears to be on Google's side.
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