Every once in a while you get a ticket that looks simple on the surface, then quietly turns into a “why is Microsoft like this” adventure.

This one started with a pretty normal request from our Controller. He wanted two shared mailboxes set up:

• receivables@zyston.com
• payables@zyston.com

Easy enough. I created the shared mailboxes, gave him access, and had him start sending from them.

Problem 1: “Why Does It Still Look Like It Is Coming From Me?”

The first thing he noticed was that even though he was trying to send from the Receivables and Payables boxes, the emails were still showing up as being sent from his personal address.

From the user side, it just feels wrong:

“If I am emailing vendors as receivables@, why does it still say it is from me personally?”

Under the hood this was a permission and From-address issue. In Exchange Online, shared mailboxes are basically headless accounts. The human needs the right permissions, and Outlook needs to actually send as the mailbox, not just “on behalf of” or as their own account.

Here is what I did to fix that part:

• Gave him Full Access to the Receivables and Payables shared mailboxes
• Gave him Send As permission on both boxes
• Walked him through Outlook so he could:
  • Turn on the From field
  • Pick receivables@zyston.com or payables@zyston.com in the From dropdown when composing

After that, new emails started landing in inboxes as actually coming from receivables@ and payables@ instead of his personal account. Ticket solved, right?

Not quite.

Problem 2: “Why Are My Sent Items Going To The Wrong Place?”

A little later he circled back with a second issue that honestly matters just as much from an accounting perspective.

When he sent emails from the shared mailboxes, the messages were showing up:

• In his personal Sent Items
• Not in the Sent folder of the shared mailboxes

So from his point of view:

“If I go into receivables@, I cannot see what Receivables actually sent. It is all buried in my personal Sent folder.”

That is a problem if multiple people ever need to work out of the same shared box or audit communication later.

The Hidden Microsoft Toggle Problem

This is where Microsoft gets cute.

You would think “send an email from a shared mailbox” would also “save a copy of that email in the shared mailbox Sent folder” by default.

Nope.

By default, Exchange Online likes to drop the sent copy into the sender’s mailbox instead. If you do not know about the hidden toggles, it just feels broken.

And of course, these toggles are not in some nice obvious GUI page like “Shared Mailbox Behavior.” They are buried behind PowerShell flags that you either know about or you do not. Very “if you know, you know.”

The two properties you care about are:

• MessageCopyForSentAsEnabled
• MessageCopyForSendOnBehalfEnabled

You have to flip those on at the mailbox level so that any Send As or Send On Behalf email also leaves a copy in the shared mailbox Sent folder.

The PowerShell Fix

Here is the exact approach I used.

First, connect to Exchange Online:

Connect-ExchangeOnline


Then, for each shared mailbox, turn on the sent-items copy behavior:

Set-Mailbox -Identity "receivables@zyston.com" `
   -MessageCopyForSentAsEnabled $true `
   -MessageCopyForSendOnBehalfEnabled $true

Set-Mailbox -Identity "payables@zyston.com" `
   -MessageCopyForSentAsEnabled $true `
   -MessageCopyForSendOnBehalfEnabled $true


If you want to be a little fancier and hit a list of mailboxes in one shot, something like this works:

$sharedMailboxes = @(
   "receivables@zyston.com",
   "payables@zyston.com"
)

foreach ($mbx in $sharedMailboxes) {
   Set-Mailbox -Identity $mbx `
       -MessageCopyForSentAsEnabled $true `
       -MessageCopyForSendOnBehalfEnabled $true
}


After running that, any time he sends as receivables@ or payables@:

• A copy lands in his Sent folder
• A copy also lands in the shared mailbox Sent folder

Now if someone opens the shared mailbox, the Sent folder actually tells the full story of what that mailbox has been saying to people.

Why This Ticket Actually Mattered

This is a good example of why “click the thing and close the ticket” is not the full job in IT.

On paper, the first ask was:

“Can you make it so emails come from receivables@ and payables@ instead of my personal account?”

I could have stopped after fixing the From-address behavior and technically, that request would have been satisfied.

But by actually talking through how he uses these mailboxes day to day, it became obvious the real problem was bigger:

• He needed clean separation between personal communication and finance communication
• He needed a record inside the shared mailbox so anyone else looking later could see what was sent

The second issue with Sent Items only comes up if you care about the user experience and the workflow behind the request, not just the checkbox on the ticket.

Sometimes the real work is:

• Listen a little longer
• Ask “what are you trying to do with this, not just what button do you want me to press”
• Dig until you find the weird hidden settings that actually make the tool behave the way they expected from the start

In this case, the fix was a couple of PowerShell lines. The value was showing the Controller that the shared mailboxes can work the way his brain already assumes they should.

That is the part he will remember the next time he needs help.