Title: Connection Error Last modified: September 16, 2026 --- # Connection Error * Resolved [Hola12345](https://wordpress.org/support/users/mridul12345/) * (@mridul12345) * [2 weeks, 3 days ago](https://wordpress.org/support/topic/connection-error-66/) * Hi * Even though my authentication to Outlook worked fine, I am getting this error * Connection needs attention: admi*****ls.com (outlook) Could not renew the Microsoft access token: Authorization Server rejected the request: AADSTS900144: The request body must contain the following parameter: ‘refresh_token’. Trace ID: db4d7e40- 7a78-48c9-9c2a-8……….. Correlation ID: 3dd05363-1f7c-4e4a……….. Timestamp: 2026- 09-15 23:47:30Z. Please reconnect this Outlook connection in FluentSMTP settings. * Please help. Viewing 5 replies - 1 through 5 (of 5 total) * Thread Starter [Hola12345](https://wordpress.org/support/users/mridul12345/) * (@mridul12345) * [2 weeks, 2 days ago](https://wordpress.org/support/topic/connection-error-66/#post-19022575) * I’ll appreciate your response ASAP since my website email stopped functioning. Thank you! * Plugin Support [Ariful Islam](https://wordpress.org/support/users/arifulislam1/) * (@arifulislam1) * [2 weeks, 1 day ago](https://wordpress.org/support/topic/connection-error-66/#post-19023748) * Hi [@mridul12345](https://wordpress.org/support/users/mridul12345/) , * Apologies for the delayed reply here. Thanks for sharing the error details. * This means the Outlook connection no longer has a usable Microsoft refresh token saved on your site, so FluentSMTP cannot renew the access token. Microsoft requires a `refresh_token` when renewing Outlook/Microsoft 365 OAuth access, and if that token is missing, expired, or revoked, the connection must be authenticated again. * Please try this: 1. Update FluentSMTP to the latest version. 2. Go to WP Admin → Settings → FluentSMTP → Settings/Connections. 3. Edit the Outlook / Office 365 connection. 4. Click Authenticate with Office365 again. 5. Complete the Microsoft login/consent flow. 6. Copy the returned code back into FluentSMTP, save the connection, then send a test email. * If the same error returns after reconnecting, please confirm: - Your FluentSMTP version - Whether you are using Outlook.com, Microsoft 365, or a single-tenant Entra app - Whether the Directory (tenant) ID field is empty or filled - A screenshot of the Outlook connection settings, with client secret/tokens hidden * Please do not share any client secret, access token, or refresh token publicly. * Thank you. * Thread Starter [Hola12345](https://wordpress.org/support/users/mridul12345/) * (@mridul12345) * [2 weeks, 1 day ago](https://wordpress.org/support/topic/connection-error-66/#post-19023840) * Thank you. Unfortunately, it solved one problem but created another. * I had 2 senders; [admin@domain.com](https://wordpress.org/support/topic/connection-error-66/admin@domain.com?output_format=md) and [no-reply@domain.com](https://wordpress.org/support/topic/connection-error-66/no-reply@domain.com?output_format=md) The [no-reply@domain.com](https://wordpress.org/support/topic/connection-error-66/no-reply@domain.com?output_format=md) sender was working perfectly before. Tested on real environment and tested with“ Send Test Email” feature. But [admin@domain.com](https://wordpress.org/support/topic/connection-error-66/admin@domain.com?output_format=md) was NOT working and that is the reason I contacted you for support. * Your solution fixed the admin@domain issue. Tested with the email test feature. But now [no-reply@domain.com](https://wordpress.org/support/topic/connection-error-66/no-reply@domain.com?output_format=md) is not sending test email. It is showing this error * “The user account which was used to submit this request does not have the right to send mail on behalf of the specified sending account., Cannot submit message.” * Could you please help. * Thread Starter [Hola12345](https://wordpress.org/support/users/mridul12345/) * (@mridul12345) * [1 week, 6 days ago](https://wordpress.org/support/topic/connection-error-66/#post-19024754) * I’ll appreciate your help. Could you please get back to me. * Plugin Support [Ariful Islam](https://wordpress.org/support/users/arifulislam1/) * (@arifulislam1) * [1 week, 6 days ago](https://wordpress.org/support/topic/connection-error-66/#post-19024775) * I’m sorry for the delayed reply. * The refresh-token issue for `admin@domain.com` appears to be resolved, but the new error with `no-reply@domain.com` is a separate Microsoft 365 permission issue. * Microsoft is rejecting the message because the Microsoft account used to authenticate FluentSMTP does not currently have permission to send as, or send on behalf of,` no-reply@domain.com`. * Microsoft is rejecting the request because the account authenticated in the FluentSMTP connection is not currently allowed to send using `no-reply@domain.com`. * Please verify the following: 1. Confirm which Microsoft account was used to authenticate the `no-reply@domain. com` connection. 2. If `no-reply@domain.com` is a separate or shared mailbox, grant the authenticated account either **Send As** or **Send on Behalf** permission for that mailbox. 3. Confirm that the Microsoft Graph delegated permission `Mail.Send.Shared` is enabled and consented. 4. Reconnect the `no-reply@domain.com` connection in FluentSMTP after confirming the permissions. 5. If `no-reply@domain.com` is only an alias, verify that it is mapped to the correct Outlook connection. * Please do not share any client secret, access token, or refresh token publicly. If the issue continues, please let us know whether `no-reply@domain.com` is a separate mailbox, shared mailbox, or alias, and which account was used during authentication. * Thank you. Viewing 5 replies - 1 through 5 (of 5 total) You must be [logged in](https://login.wordpress.org/?redirect_to=https%3A%2F%2Fwordpress.org%2Fsupport%2Ftopic%2Fconnection-error-66%2F%3Foutput_format%3Dmd&locale=en_US) to reply to this topic. * ![](https://ps.w.org/fluent-smtp/assets/icon.svg?rev=2458343) * [FluentSMTP – WP Mail SMTP Plugin with Amazon SES, SendGrid, Mailgun, Postmark, Cloudflare, toSend, Gmail and Any SMTP](https://wordpress.org/plugins/fluent-smtp/) * [Frequently Asked Questions](https://wordpress.org/plugins/fluent-smtp/#faq) * [Support Threads](https://wordpress.org/support/plugin/fluent-smtp/) * [Active Topics](https://wordpress.org/support/plugin/fluent-smtp/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/fluent-smtp/unresolved/) * [Reviews](https://wordpress.org/support/plugin/fluent-smtp/reviews/) ## Tags * [connection error](https://wordpress.org/support/topic-tag/connection-error/) * [outlook](https://wordpress.org/support/topic-tag/outlook/) * 5 replies * 2 participants * Last reply from: [Ariful Islam](https://wordpress.org/support/users/arifulislam1/) * Last activity: [1 week, 6 days ago](https://wordpress.org/support/topic/connection-error-66/#post-19024775) * Status: resolved