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Force AD replication and then try again
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Thank you Mahesh. Force AD replication. Same error
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can you go to user1 account properties in AD and check if actual &quot;send as&quot; permissions are set for user2 or not<br />
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if not assign there, force ad replication and check if it works
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AD properties did not &nbsp;have the send as permission for user2, however after I add user2 to send as permissions, still getting the same error (I did the AD replication)
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allow some time for exchange to understand that permissions has been set (may be 8 HRS)
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ok. I will try it again tomorrow. Thank you
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Did you close and reopen Outlook on the client PC after making the change? Normally, when you grant them Full Access permission to another account, it will show up in the column underneath their own inbox.
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William, I did close and reopen Outlook, same error. Thank you
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send as and send on behalf are 2 different things, what version of exchange are you running? on exchange 2010 &gt;&nbsp;recipient configuration &gt;&nbsp;mailbox &gt;&nbsp;right clicking on a user manages send as permission. To manage send on behalf you need to open the properties. then go to the mail flow settings , Delivery options and then send on behalf of is there.<br />
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send as is when user 2 opens their outlook and changes the from address to user 1's email address giving the impression to the receiver that it has actually come from user 1<br />
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send on behalf will say on the email when its sent &quot;user 2 on behalf of user 1&quot;
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Daryl, thank you for your reply, I am trying ti send as. I'm running Exchange 2010
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What do you mean by cached email account?<br />
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Like i told you earlier Send as is set at ntfs level and when you send email with send as exchange checks ntfs permissions at AD level and not with your cached account level<br />
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Enough time has passed after you configured send as permission and hence it started working
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I have applied send as permissions and full access &nbsp;to user1 mailbox from user2. When I try to send an email from user2 account using user1 email it fails &nbsp;with:&quot;You can't send a message on behalf of this user unless you have permission to do so. Please make sure you're sending on behalf of the correct sender, or request the necessary permission&quot;
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I have applied send as permissions and full access  to user1 mailbox from user2. When I try to send an email from user2 account using user1 email it fails  with:"You can't send a message on behalf of this user unless you have permission to do so. Please make sure you're sending on behalf of the correct sender, or request the necessary permission"

Send as permission on Exchange

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.