Exchange Online
48 articles tagged Exchange Online.
Block legacy authentication in Microsoft 365 without breaking printers
Find every device and app that still signs in with legacy authentication, move printers and scanners to a supported sending method, then block legacy auth with Conditional Access.
Build Purview DLP policies for Exchange, SharePoint, Teams and devices
Step-by-step Microsoft Purview DLP setup that stops card numbers and PII leaking through email, SharePoint, OneDrive, Teams chat and Windows or macOS devices, with a safe simulation rollout.
Calendar permissions in Exchange Online: Add-MailboxFolderPermission guide
Share calendars, change the organization-wide Default permission and add calendar delegates in Exchange Online with Add-, Set- and Remove-MailboxFolderPermission, including localized folder names.
Compromised Microsoft 365 account runbook: contain, investigate, recover
A step-by-step runbook for a confirmed Microsoft 365 account takeover: disable and revoke, remove attacker persistence, scope the breach with audit logs and restore the user safely.
Configure ARC trusted sealers and Enhanced Filtering for an email gateway
Stop SPF, DKIM and DMARC failures on mail that reaches Exchange Online through a third-party gateway by combining Enhanced Filtering for Connectors and ARC.
Control the new Outlook for Windows rollout with policies and toggles
The admin controls for new Outlook for Windows: hide the toggle, stop automatic migration, block the app or mailbox access, and migrate on your own schedule before the March 2027 opt-out.
Convert a user mailbox to a shared mailbox and remove the license safely
Keep a leaver's email and calendar in Exchange Online without paying for a license: secure the account, convert the mailbox, grant access, then remove the license in the right order.
Email migration cutover checklist: DNS TTLs, MX switch and day one
A practical cutover runbook for moving a domain's mail to Exchange Online: lower TTLs early, switch MX and Autodiscover safely, and support users on day one.
Enable inbound SMTP DANE with DNSSEC in Exchange Online and switch your MX
Step-by-step: move an Exchange Online accepted domain to its DNSSEC-capable mx.microsoft MX record, then turn on inbound SMTP DANE and verify the TLSA records.
EWS retirement in Exchange Online: find EWS apps and set EWSAllowedAppIDs
Find every app that still calls Exchange Web Services, build an EWSAllowedAppIDs allow list and set EWSEnabled so critical apps keep working while EWS is switched off from October 2026.
Exchange 2016 and 2019 end of support: move to Exchange SE or Online
Exchange 2016 and 2019 are out of support and the paid ESU ends with October 2026. Choose between Exchange Server SE and Exchange Online, then plan the upgrade or migration.
Exchange hybrid remote move migration: endpoints, batches and completion
Move mailboxes from on-premises Exchange to Exchange Online with remote move migration: enable MRS Proxy, test the endpoint, build batches, schedule completion and clean up.
Exchange Online connectors explained: inbound, outbound and partner setups
Know when Exchange Online needs a connector, then build partner, gateway and on-premises connectors with forced TLS, IP or certificate restrictions and validation.
Exchange Online mail flow rules: disclaimers, external tags and blocking
Build Exchange Online mail flow rules for outbound disclaimers, external sender warnings and attachment blocking, then test, order and troubleshoot them in the EAC and PowerShell.
Exchange Online migration batch stuck on Syncing: causes and fixes
Find out why an Exchange Online migration batch sits on Syncing, read the per-user stall reasons in PowerShell, and apply the right fix for concurrency, throttling, source health or skipped items.
Find and remove malicious inbox and forwarding rules after a BEC
After a compromised mailbox, find hidden inbox rules, SMTP forwarding and delegate access in Exchange Online, remove them safely and block external auto-forwarding so the attacker can't come back.
Fix 550 5.1.8 Access denied, bad outbound sender in Exchange Online
Why Exchange Online blocks a user with 550 5.1.8, how to secure the account first, and how to remove it from Restricted entities in the Defender portal or with Remove-BlockedSenderAddress.
Fix 550 5.4.1 Recipient address rejected: Access denied in Exchange Online
Find out why Directory-Based Edge Blocking rejects inbound mail with 550 5.4.1 and fix it for whole domains, hybrid recipients, public folders and dynamic groups.
Fix 550 5.7.30 Basic authentication is not supported for Client Submission
A printer, scanner or app stopped sending mail through Exchange Online with 550 5.7.30. Find the sender and move it to OAuth, High Volume Email or an SMTP relay connector.
Fix DKIM CnameMissing in Microsoft 365 and enable signing for your domain
Why Microsoft 365 reports CnameMissing when you enable DKIM, how to publish the exact selector CNAME records, and how to confirm the domain signs mail.
Fix Entra Connect AttributeValueMustBeUnique and duplicate proxy addresses
Find which object already holds the duplicated proxyAddresses or userPrincipalName value, remove it from the right side, and confirm the next Entra Connect sync exports cleanly.
Fix Microsoft 365 email going to Junk by reading SFV, CAT and compauth
Work out why Exchange Online delivered a message to Junk Email from its anti-spam headers, then apply the fix that matches the component that filtered it.
Fix TooManyBadItemsPermanentException in Exchange Online mailbox moves
Find out why a mailbox move fails with TooManyBadItemsPermanentException, read the bad items in the move report, and complete it with skipped-item approval or a permissions cleanup.
Full Access, Send As and Send on Behalf in Exchange Online with PowerShell
Grant, remove and audit the three mailbox delegation permissions in Exchange Online with PowerShell, control Outlook automapping, and fix the errors delegates hit most often.
High Volume Email for Microsoft 365: set up HVE for app and device mail
Create High Volume Email accounts, connect pay-as-you-go billing, choose basic auth or OAuth, and point printers and line-of-business apps at the HVE endpoint for internal mail.
IMAP to Exchange Online migration from cPanel and other hosts
Move mailboxes from cPanel or any IMAP host to Exchange Online with migration batches: CSV prep, endpoint, PowerShell, MX cutover and the cPanel email routing setting that catches people out.
Import PST files to Exchange Online with network upload and AzCopy
Bulk-import PST files into Exchange Online mailboxes and archives with the Microsoft Purview Import service: SAS URL, AzCopy upload, mapping CSV, filtering and retention hold.
Litigation hold vs retention policy vs eDiscovery hold for Exchange
Which preservation method to use for Exchange Online mailboxes: how Litigation Hold, Purview retention policies and eDiscovery holds differ, how to apply each, and how to see which holds a mailbox has.
Message trace in Exchange Online: the new EAC and Get-MessageTraceV2
Trace a missing email with the new message trace in the Exchange admin center, Get-MessageTraceV2, the Graph message trace API and historical searches.
Microsoft 365 audit log search: who deleted, shared or forwarded what
Use Microsoft Purview Audit and Search-UnifiedAuditLog to find who deleted a file, shared a link, purged email or created a forwarding rule, then export and read the AuditData.
Migrate EWS apps to Microsoft Graph before Exchange Online turns off EWS
Move mail, calendar and contact integrations from EWS to Microsoft Graph: map operations, replace impersonation with scoped permissions, convert stored IDs and plan for gaps.
Migrating public folders to Exchange Online with batch migration
Move modern public folders from Exchange Server 2016, 2019 or Subscription Edition to Exchange Online with the native batch migration: scripts, mapping CSV, lock-down, completion and verification.
Outlook Autodiscover problems with Microsoft 365: DNS checks and fixes
Fix Outlook profiles that can't find an Exchange Online mailbox: check the Autodiscover CNAME, root domain responses, cached URLs, registry and Group Policy settings.
Purview eDiscovery: run cases, legal holds, searches and exports
A practical walkthrough of the unified eDiscovery experience in the Microsoft Purview portal: permissions, cases, hold policies, searches, statistics and exports, with limits and fixes.
Purview retention policies and labels: meet retention, avoid data loss
How Microsoft Purview retention policies and retention labels work across Exchange, SharePoint, OneDrive and Teams, which settings win, and how to roll them out without deleting content by accident.
Recoverable Items folder full in Exchange Online: diagnose and fix
Find out why a mailbox's Recoverable Items folder hit its quota, which hold is keeping the data, and how to free space with an archive, a retention tag or a reviewed hold change.
Reject Direct Send in Exchange Online without breaking printers and apps
Block spoofed Direct Send mail with RejectDirectSend while keeping approved printers, apps and SaaS senders working through partner inbound connectors.
Remove the last Exchange server from a hybrid Exchange Online setup
Transfer Exchange-attribute source of authority to the cloud, tear down the hybrid configuration and uninstall the last on-premises Exchange server.
Safe Links and Safe Attachments in Defender for Office 365, explained
How Safe Links and Safe Attachments policies protect email, Teams and Office files, how Built-in protection differs from Standard and Strict, and how to configure, test and troubleshoot them.
Scope Graph Mail.Send to specific mailboxes with RBAC for Applications
Limit an app's Microsoft Graph Mail.Send permission to the mailboxes it really needs with RBAC for Applications in Exchange Online, then remove the tenant-wide grant in Entra ID.
Shared mailbox vs Microsoft 365 group vs distribution list: which to use
Compare shared mailboxes, Microsoft 365 Groups, distribution lists, mail-enabled security groups and dynamic distribution groups, with limits, licensing and PowerShell to create each one.
SMTP AUTH vs Direct Send vs relay connector: sending mail from devices
Compare SMTP AUTH, Direct Send, an SMTP relay connector, High Volume Email and Azure Communication Services, and pick the right way for printers and apps to send through Microsoft 365.
SMTP AUTH with OAuth client credentials for apps on Exchange Online
Move an application from Basic auth SMTP to OAuth: register an Entra app with SMTP.SendAsApp, register its service principal in Exchange Online and send with SASL XOAUTH2.
SPF, DKIM and DMARC for Microsoft 365: set up, test and reach p=reject
Publish SPF, enable DKIM signing and roll DMARC out from p=none to p=reject for Microsoft 365 custom domains, with DNS examples, PowerShell commands and header checks.
Stop Outlook asking for your password again and again in Microsoft 365
Find out why Outlook for Windows keeps prompting for credentials with Microsoft 365, then fix WAM, profile, hybrid and session policy causes.
Tenant External Recipient Rate Limit (TERRL): monitor it and fix 5.7.233
How the Exchange Online tenant-wide external recipient limit is calculated after the 2026 changes, how to monitor it in the EAC and PowerShell, and what to do when users get 550 5.7.233.
Google Workspace to Microsoft 365 Migration: A Complete Technical Guide for Mail, Calendar, Contacts and Drive
A step-by-step guide to moving from Google Workspace to Microsoft 365 with Exchange Online's native Gmail migration and Migration Manager, from routing subdomains and service accounts to MX cutover.
Microsoft 365 Tenant-to-Tenant Migration Architecture: Cross-Tenant Mailbox, OneDrive, Teams and Domain Move
A practical guide to Microsoft 365 tenant-to-tenant migration for mergers and divestitures: native cross-tenant mailbox and OneDrive moves, SharePoint, Teams and the domain cutover.