Exchange 2016 and 2019 End of Life and Some Interesting Exchange Online Developments
On Oct 14, 2025, Exchange 2019 and 2016 reach end-of-life and Exchange SE becomes the only supported on-premises Exchange server. In other news, we discuss Microsoft guidance for moving to cloud first identity, HVE and ECS and the extension of basic authentication support to September 2028, the introduction of auto-archiving for Exchange Online, and why Microsoft is deprecating the Contact object from Exchange Online. https://office365itpros.com/2025/10/09/exchange-se-news/
Exchange Migration Cross forest
Hello, I planning to do an exchange Migration from forest A to forest B and the email address will be changed. I don't want to set any trust between the two, i will simply create the active directory users from scratch with new passwords and will install and configure the exchange environment in the target forest and will create the mailboxes. i will use a third-party tool to migrate the mailboxes between the two forests and after cutover i will add the alias of the old email as additional proxy address to the mailboxes. i am assuming everything will work fine however i have seen lot of articles on the internet about we have to migrate the legacyexchangeDN from the source environment and to add it as X500 proxy address as well in the destination or we might face issues in the migrated recurrent meetings when someone wants to edit or when someone reply to a migrated email.... I can afford having some meeting corrupted after migration but i cant afford the headache of NDR when someone reply to the migrated emails it will be a disaster.... anyone had this experience before to share it with me especially regarding the reply to the migrated emails and i did not lot of documentation from Microsoft about such scenario? Thank You.
Exchange 2019 Mailbox Migration Error - Folder conflicts with Exchange Online folder
Hi Exchange Experts, I'm migrating a small Exchange 2019 environment to 365. Been pulling my hair out becuase of just one mailbox giving this error Error description --------------------------- Error: AggregateMailboxFolderConflictPermanentException: The folder 'Files' conflicts with Exchange Online folder 'Files', please move the messages to another folder and restart the job. Data migrated: 0 B (0 bytes) Migration rate: -------------------------------------- Migration user report: 5/14/2025 12:32:05 PM [MEUP300MB0105] Request processing continued, stage CreatingFolderHierarchy. 5/14/2025 12:32:05 PM [MEUP300MB0105] Stage: CreatingFolderHierarchy. Percent complete: 10. 5/14/2025 12:32:12 PM [MEUP300MB0105] Stage: CreatingFolderHierarchy. Percent complete: 10. 5/14/2025 12:32:12 PM [MEUP300MB0105] Fatal error AggregateMailboxFolderConflictPermanentException has occurred. ---------------------- It seems to be a system folder and I've tried to remove files from it (although there're no files in it) using MFCMAPI tool with no success. Renamed the folder and tried to re-run the migration with no luck. Has anyone experience this issue? any thoughts or tips are much appreciated ! Thank you.Exchange 2016 to SE and Exchange Online questions
Hi, We're currently in the process of migrating from Exchange 2016 to Exchange Subscription Edition (SE), along with moving a portion of our mailboxes to Exchange Online. We have approximately 3,000 mailboxes, and around 2,000 of those will eventually end up in Exchange Online—for various reasons (don’t ask why…). I have a few questions I'd like to clarify and hope you can assist: Exchange On-Premises Questions: If a user mailbox is moved to Exchange SE, can they still access shared or user mailboxes that remain on Exchange 2016? Do we need to migrate them in the same batch to preserve access/permissions? (should't be an issue in the same Exchange Org right?) If a shared mailbox is migrated to Exchange SE while the user mailbox remains on Exchange 2016, will access still work? Do we need to point the Hardware Load Balancer (HLB) to the new Exchange SE servers before mailbox moves to allow proper client connectivity and proxying back to Exchange 2016? Or is it okay to keep the HLB pointed to the Exchange 2016 servers until all migrations are complete and then switch it over? Proxy upwards from Exchange 2016 to Exchange SE? What’s the best practice here? Pros/cons? Exchange Online Questions: If we want all outbound mail to go through the on-prem Exchange environment—even for Exchange Online mailboxes—is this configured via the Hybrid Configuration Wizard (HCW)? Is the Litigation Hold status preserved when migrating a mailbox to Exchange Online? Can a mailbox hosted in Exchange Online access a shared mailbox still residing on-prem? (Should't be an issue right?) Can an on-prem mailbox access a shared mailbox that has been migrated to Exchange Online? For mailboxes with Full Access or Send As permissions (e.g. user mailboxes tied to shared mailboxes), do they need to be migrated together in the same batch to retain functionality? We’ll be using native Microsoft migration tools (no 3rd-party solutions). If I recall correctly, separate migrations will still allow Full Access?!?, but Send As may not work properly unless migrated together. Is that still accurate?
Exchange 2016 and deffer delivery
Hi! Is it possible to configure delay of outgoing sending messages for user mailbox, like outlook's deffered delivery? I couldn't find such an option in mailflow-rules, as deepseek says "New-TransportRule -Name "DelaySendForUser" -SenderAddressEquals "email address removed for privacy reasons" -DeferMessageMinutes 2 -Enabled $true" - it doesn't work:))Hotfix update for 2016 CU23 HU18: (KB5066370) breaks OWA and leaves all services disabled
Has anyone else applied the latest hotfix? First of all it tries to validate open files instead of just killing these processes as part of the update, then after rebooting all the services are left in a disabled state. Then I discover it has broken IIS and OWA doesnt work. We have had client issues all day in the office. It looks like another update has been pushed out without sufficient testing. Any help would be grateful at this point, I am looking to take 2 out of 4 servers offline.
How to perform Windows Update for Exchange 2016 DAG Cluster
Hello, I need to install windows server security update on Exchange 2016 DAG which require reboot the server. I will install the updates on the first server Tuesday, and the seconde server on Wednesday. I'm wondering if installing patches on separated days may impact Exchange services, also i need to know the steps to follow before restart each server after installing the patch.Applying On-Prem EAP with New-Remote Mailbox
BACKGROUND: my org is in a hybrid AD/Exchange environment, and will remain so for some time. All mailboxes, other than a very small number with on-prem dependencies, were migrated to M365 a few years ago; we will continue to have 1-2 Exchange Servers on-premises for both management and some legacy on-prem processes. All user accounts are created on-premises, and synchronized to M365 through Entra Connect Sync. Our on-prem EAP has the exact address syntaxes that we need [applies to "Users with Exchange mailboxes" + "Resource mailboxes" + "Mail-enabled groups"]. I haven't found a clear answer to the question: with an Exchange 2019 (and soon SE) server on-premises - with users initially created on-premises - is there a way to provision new EXO mailboxes [using the 'new-remotemailbox' cmdlet], such that the on-prem EAP applies during creation? I've been working with these two references, but so far haven't found a way to make the "new-remotemailbox..." cmdlet work to (a) create a new account on-premises and (b) ultimately have an EXO mailbox provisioned with the on-prem EAP addresses in place: On provisioning mailboxes in Exchange Online when in Hybrid | Microsoft Community Hub https://learn.microsoft.com/en-us/powershell/module/exchangepowershell/new-remotemailbox?view=exchange-ps Any thoughts or suggestions would be welcomed! (OR - perhaps it just can't be done?)
