Sign-in & Login Problems

How to Fix Repeated Microsoft 365 Sign-In Prompts and Outlook SMTP Errors

Khadija Khan Oct 8, 2026 870 views

Question details

The user is experiencing repeated Microsoft 365 sign-in prompts in applications like Excel, alongside SMTP connection errors when trying to use a RoadRunner email account in Outlook.

How to Fix Repeated Microsoft 365 Sign-In Prompts and Outlook SMTP Errors

Product: Microsoft 365
Device & OS: Windows
Scenario: Attempting to use Excel without constant authentication interruptions and trying to successfully send emails via Outlook.
Observed behavior: Excel and other Office applications repeatedly display a prompt asking the user to sign in, while Outlook fails to connect to the outgoing mail server due to SMTP errors.

Before you start

Before beginning, ensure you have your correct Microsoft account password and the latest SMTP server settings provided by your email service provider.

Solution 1Recommended

Update Software and Refresh Account Credentials

Use this solution to clear outdated cached credentials and ensure your Windows operating system and Office applications are fully updated to prevent authentication loops.

Persistent sign-in prompts are often caused by a mismatch between cached credentials and outdated Windows or Office software. Logging out completely and using your master Microsoft password instead of a Windows Hello PIN can reset this connection.

Update Windows and Office

Go to Windows Settings > Update & Security > Windows Update and check for updates. Open any Office app like Excel, navigate to File > Account, and select Update Options > Update Now.

Sign Out of Microsoft 365

In Excel or Word, go to File > Account. Under User Information, click 'Sign out' for all connected accounts, then close all Office applications.

Restart Your Computer

Reboot your Windows PC to ensure all temporary cached sessions and background Office processes are fully cleared.

Sign In Using Account Password

Open Excel. When prompted to sign in, enter your Microsoft account email. If given the option to use a Windows Hello PIN, choose 'Use a password instead' and enter your Microsoft account password.

Update Software and Refresh Account Credentials

Credential Refresh Complete: Bypassing the Windows Hello PIN forces Office to securely re-authenticate with Microsoft servers, which often stops the persistent prompting.

Solution 2

Run the Microsoft 365 Repair Tool

If updating and re-authenticating doesn't stop the prompts, repairing the Office installation can fix corrupted system files causing the loop.

Solution 3

Update Outlook SMTP Settings for Your Email Provider

Resolve Outlook sending errors by ensuring your outgoing mail server (SMTP) settings match your provider's current requirements.

Free Microsoft Office alternative

Tired of Microsoft 365 Sign-In Issues? Try WPS Office

If repeated sign-in prompts and complex Outlook configuration errors are disrupting your productivity, consider switching to WPS Office. It provides a lightweight, highly compatible, and hassle-free alternative to Microsoft Office without the constant authentication interruptions.

1. Download the Free Installer: Visit the official WPS website to download the lightweight setup file for Windows.
2. Install in Minutes: Run the installer. WPS Office sets up quickly and integrates smoothly with your local file system.
3. Open Office Files Directly: Double-click your existing documents, spreadsheets, or presentations to open them instantly without sign-in barriers.

Seamlessly compatible with Microsoft Excel (.xlsx), Word (.docx), and PowerPoint (.pptx) formats.Work locally without persistent sign-in prompts interrupting your daily workflow.Lightweight installation that runs smoothly on almost all Windows devices.Familiar tabbed user interface makes migration easy and intuitive.

microsoft office alternative - wps office

Frequently Asked Questions

Why does Excel keep asking me to sign in?

Excel may repeatedly prompt for sign-in if your Windows or Office software is outdated, if the cached login credentials have become corrupted, or if there is an issue with your Microsoft account subscription status.

What is an Outlook SMTP error?

An SMTP (Simple Mail Transfer Protocol) error indicates that Outlook is failing to connect to your email provider's outgoing mail server. This usually happens when the server address, port number, or encryption method in your settings is incorrect or outdated.

Should I use a Windows Hello PIN for Microsoft 365 sign-in?

While a PIN is convenient, if you are experiencing sign-in loops, it is recommended to click 'Use a password instead' and enter your full Microsoft account password. This forces the system to perform a fresh authentication with Microsoft's servers.

How do I find the correct SMTP settings for my email account?

You should visit the official support website of your email service provider (such as RoadRunner, Gmail, or Yahoo) and search for 'IMAP/SMTP settings'. They will list the exact server addresses, ports, and encryption types required for third-party clients like Outlook.

Login & Account Issues