I just got my new tablet device and tried setting up my Microsoft 365 email account on it. The setup seemed to work fine at first because I could see all my emails in the inbox. But when I try to send any email, I keep getting this error message:
535 5.7.139 Authentication unsuccessful, SmtpClientAuthentication is disabled for the Tenant
I did some research and found out that Microsoft has turned off basic SMTP authentication for security reasons. Most devices now need to use OAuth 2.0 for sending emails through Microsoft servers.
I’m wondering if there are any workarounds for this issue or if the device manufacturer plans to add OAuth 2.0 support in future updates. Has anyone else run into this problem with their email setup?
I tried creating an app password but that didn’t seem to work either. Right now I can only receive emails but can’t send any, which makes the email feature pretty useless.
I encountered a similar problem while setting up my work email on a different device. The trick that worked for me was to ask our IT team to enable SMTP AUTH specifically for my account via the Exchange admin center. They used a PowerShell command to allow it just for my mailbox, while it remained disabled for others, preserving security. In case you lack admin rights, consider using IMAP instead of Exchange if your device permits, although this might limit some synchronization capabilities. Ultimately, it will be up to the manufacturer to provide the necessary firmware updates for OAuth 2.0 support.
This authentication issue has become increasingly common since Microsoft tightened their security policies. I ran into this exact problem when deploying several tablets at our office. The solution that worked consistently was enabling modern authentication in the Exchange Online PowerShell. Your administrator needs to run Set-OrganizationConfig -OAuth2ClientProfileEnabled $true and then configure the specific mailbox with Set-CASMailbox -Identity [email] -SmtpClientAuthenticationDisabled $false. However, this requires enterprise admin privileges. For personal accounts, I found that configuring the email as IMAP/SMTP with server settings smtp-mail.outlook.com on port 587 with STARTTLS sometimes bypasses the OAuth requirement, though Microsoft is gradually closing these workarounds. The most reliable long-term solution remains waiting for your device manufacturer to implement proper OAuth 2.0 support in their mail client.
Had the exact same headache with my new device last month! What finally worked was switching to the outlook app instead of the native mail client. microsoft’s own app handles the oauth stuff automatically so no more authentication errors. bit annoying to use seperate app but atleast everything works properly now.