Proxy addresses broken after enabling Azure AD Connect

[felixtech]

Hi everyone,

we were using Exchange Online with built-in authentication. Each user has 2 SMTP e-mail address types configured as well as multiple shared mailboxes open. When creating a new e-mail each user was able to select the e-mail address he wanted to send from.

Then I enabled Azure AD Connect to sync the local directory to the cloud via e-mail address matching.

Since then every user can receive via both addresses but can only send from the address with the same domain as the local logon domain. Also it is impossible to select a shared mailbox as the sender. The proxy addresses and shared mailbox delegations are still configured but Outlook and OWA just ignore this configuration.

Best regards,

Felix

[#2]

Send as in SendAs or SendOnBehalf?
Send on Behalf replicates through ADConnect- could it be that it has overwritten your configuration in EXO?
SendAs should be no problem.
Since you mention receiving still works, I assume switching ADConnect on and matching worked out ok.

[#3]

Both. The "From" dropdown in Outlook isn't even shown anymore.
I have checked EXO configuration. The delegations and the address-types are still in place.
The AD sync works properly and SSO also does work. The only issue is that no user can select his 2 addresses and also not select shared mailboxes.

[#4]

Are the mailboxes located in Exchange Online? I believe the functionality to select the sending SMTP alias that is used is still in preview (https://techcommunity.microsoft.com/t5/exchange-team-blog/sending-from-email-aliases-public-preview/...).
With delegate access, are the two mailboxes located in the same location (both on-prem or both in EXO). I always recommend having the delegates in the same location, even though it is supposed to work when they are not.

[#5]

All mailboxes are EXO only. The whole system started as EXO only - there has never been an On-Prem install.
The basic feature to SendAs and SendOnBehalf has worked for me forever and if that wouldn't work that would completely invalidate mailbox delegations.
The menu point as described in the blog article doesn't even exist for me anymore. Since activating AD sync all options for this have disappeared even though they existed forever before. Also disabling AD sync didn't revert the breakdown.

Edit:

After a further test I found out that I can SendAs a shared mailbox by manually typing the From address in Outlook Desktop (dropdown is missing). But I cannot SendOnBehalf a shared mailbox and I cannot send as my second proxy address.

[#6]

Sorry, your initial post didn't indicate you were using SendAs and SendOnBehalf. I had though you were just trying to send as an alias SMTP address.
Do you see the From field at all? You can turn it on by opening a new message and going to Options -> From
Is this working from Outlook on the Web?

[#7]

@Dan SnapeWhat I expect is that I click New E-Mail and then click the From dropdown and then I should be able to select my own proxy addresses as well as the addresses of the shared mailboxes I'm allowed to SendAs and/or SendOnBehalf.

Per default I do not see the From field. When I manually enable it in the settings then I see only my own primary address to choose from. My proxy address and the shared mailboxes are missing completely.

[#8]

Isnt the problem that you overwritten the users with the local domain user?

Does the local domain have also an exchange schema installed?

When you use adconnect the local user is the leading user for properties etc. From cloud only to a synced user.

[#9]

The local domain does not have an Exchange schema. There was never a on-prem Exchange. We started with EXO.

[#10]

Read the blog I posted above about the current status of changing the "From" address to one of your own SMTP proxy addresses.
If you are looking at Send As or Send-On-Behalf, you'll need to type the address in and select it...I don't believe they are automatically included in the drop down list. In OWA you can switch to the required mailbox and send.

[#11]

@felixtech 

As @Dan Snape has mentioned + has linked to an article about, SendFromAlias is a preview feature that needs to be enabled for your Organization

You can use the following PowerShell to check the current status:

Get-OrganizationConfig | Select-Object SendFromAliasEnabled

As for the SendAs/SendOnBehalf ensure that the mailbox isn't hidden from the GAL

[#12]

@Dan SnapeThe thing is all of this has worked for many, many years and it also has worked before I turned on AAD Connect. There has to be a drop-down with all my aliases and shared mailboy addresses as it has been basically for my entire life. And going to OWA to a specific shared mailbox to reply to an e-mail is at max a temporary workaround and not a solution.

[#13]

I have now enabled this setting but nothing has changed.
We don't have anything that is hidden from the GAL.