What you’re seeing
- Sending from a shared mailbox produces a bounce saying you don't have permission to send on behalf of the specified user.
- The user can open and read the shared mailbox but every reply from it fails.
- Messages go out showing 'on behalf of' the user's own name instead of appearing to come from the shared address.
- Permissions were just granted, yet the error continues.
Common causes
Every environment is different, but these are the causes our engineers find most often:
- The user has Full Access to read the mailbox, but Send As or Send on Behalf was never granted separately.
- The permission was granted recently and hasn't yet taken effect, or Outlook is still using cached information.
- Outlook's autocomplete is choosing an outdated version of the shared address from before a change or migration.
- The From field is set to a different shared address, or an alias the user has no rights to.
- In a hybrid environment, the user and the shared mailbox are in different locations and send permissions don't carry across.
Why it matters
Teams that reply to customers from a shared address can't do their jobs when sending fails. Replies either don't go out or go out from personal addresses, so customer conversations split across inboxes and the team loses track of who answered. Mixing up 'send as' and 'send on behalf' also changes how your business appears to recipients, which matters for brand consistency and sometimes for compliance records.
How AskTechGurus fixes it
Skip the trial and error. A certified engineer works on your actual system, finds the root cause, and fixes it properly.
Tell us what’s happening
Submit a ticket in about two minutes. Paste the error, describe what changed, and pick your tier. No charge to submit.
A certified engineer diagnoses it
A vetted, US-based systems engineer claims your ticket, usually within minutes during business hours, and investigates over a secure remote session you can watch and end at any time.
Fixed and verified with you
The engineer resolves the root cause and confirms with you that it’s working. You don’t just get a workaround, and you get a plain-English summary of what was wrong.
Pay only when it’s resolved
Fixed price from $99, invoiced only after you approve the fix. If it isn’t resolved, you don’t pay.
Frequently asked questions
What's the difference between 'send as' and 'send on behalf'?
Send as makes the message appear to come from the shared address alone. Send on behalf shows both names, such as 'Jane on behalf of Sales'. Which one is right depends on how you want customers to see your replies.
Will fixing this change anything for other users?
No. Send permissions are given per person, so only the users you choose are affected, and we confirm the list with you before making changes.