New for Office 365 Exchange in 2021: Send using Mailbox Alias Addresses
New users to Office 365's Exchange Online frequently ask how to send email from secondary addresses on their Exchange mailbox:
I have an Office 365 account and have set up two domains @a.com and @b.com. My user's primary email address is email@example.com however there are times I want to SEND FROM firstname.lastname@example.org from Outlook desktop application. How can I do this?
I have an Office 365 Exchange subscription for myself and have 3 different email addresses assigned to my mailbox. I receive email from all addresses in OWA, but I can only send email from one of the email addresses. How can I setup the other 2 email addresses to be able to send email from them, and display them as the sender address?
The answer to either question used to be "You can't". Now you can, if you have an Office 365 mailbox and the email administrator enabled SendFromAliasEnabled. If you are using Office 365 Exchange Online, see Send using Mailbox Alias Addresses for instructions to send from aliases.
If you don't have Office 365 Exchange Online, while you can add additional SMTP addresses to an Exchange mailbox, you can only send mail from the default email address assigned to the account. The additional accounts are receive-only addresses.
Depending on your needs, you (the email administrator) could create a shared mailbox for each address, which would save you the cost of additional mailboxes. If you need separate logins, you'll need to pay for mailboxes, but could use the lowest cost Exchange Online plan (currently $4US per month).
When you use separate accounts (mailboxes), you can send from any of the addresses. In OWA you'd need to open a in-private browser to send and receive mail from each account (unless they were setup as shared mailboxes with my main account having full Send As permission on the account). Outlook desktop supports multiple accounts in the profile, so you could have all mailboxes in a single Outlook profile and send with the correct From address.
Otherwise, there are two options: Create a send-only POP account or an IMAP account to send mail from that address or remove the address from your mailbox and create a single-member distribution group (distribution list), mail contact, or shared mailbox for the address then give your mailbox Send as permissions.
Generally speaking, using a distribution group is the easiest solution to configure. Office 365 administrators can do everything in the online interface.
If you receive a lot of mail to the second address, a shared mailbox keeps the mail separate from the mail sent to your mailbox. Replies to messages in the shared mailbox will use the shared mailbox address but you’ll need to select the shared mailbox’s address to send new messages using it.
A distribution group will receive the messages and distribute the messages to your mailbox, instead of the messages being delivered directly to your mailbox. The only difference is that the To field will list the group name, not your mailbox name. For both new messages and replies you’ll need to select the group address as the From address. Mail contacts work much the same way, except transport (mail flow) rules are used to redirect mail sent to a mail contact.
To create a distribution group or mail contact and give a user send as permission, you need to follow these steps:
For a Distribution Group:
- Create a distribution group and assign the address to the group
- Make your user account the only member of the distribution group and give it send as permission
To create a Mail Contact:
Remove the address from mailbox
Log into the Exchange admin center and select recipients then mailboxes.
To remove second address from mailbox, select the mailbox name and click the Pencil icon (Edit), or double click on the mailbox name. Select email address from the list on the left, then select the email address you want to remove and click the minus icon. Click Save to save changes and close the dialog.
Using a distribution group
Step 1: Create the new distribution group
Next, you need to create a distribution group and assign the address to it. Still in the recipients section, select groups from the row above the mailboxes. Click on the plus sign and select Distribution group.
Create the new distribution group using the alias you removed earlier. Select the correct domain from the domain dropdown. Add group owners as members should be checked by default. If you are creating a group for other users, their name should be in the Owners list.
Wait a few minutes for the Active Directory to update and replicate then double click to open the newly-created group and continue with the next step.
Step 2: Assign Send As permissions
Your user account is the only member of the group and it needs Send As permission. You will probably want to allow outsiders to send to the group address.
To make these changes, click the Pencil icon to open the group for editing. If you want to allow anyone on the internet to send mail to this address, select delivery management and choose Senders inside and outside of my organization.
Select group delegation. Add your account (or the group owner’s account) under Send As. Click Save to save the changes and close the dialog.
Using a Mail Contact
In older versions of exchange, many Exchange server administrators configured Mail Contacts and assigned Send As permission to other users in Active Directory Users and Computers and configured the contact to forward mail to a mailbox.
This is possible in Office 365 Exchange Online using the Add-RecipientPermission cmdlet and mail flow rules.
Step 1: Create the Contact
Log into the Exchange admin center and select recipients then contacts.
Create a new Mail Contact .
If you prefer using PowerShell, the cmdlet is
New-MailContact -Name "displayname" -ExternalEmailAddress email@example.com -FirstName fname -LastName lname
Step 2: Create a Mail Flow Rule
Click the Mail flow link then the plus sign, selecting Create a new rule.
- Enter a name for the rule.
- Select Apply this rule if and choose the recipient is... .
- If you used a unique display name for your contact, select it and click Add. If you used the same display name as a mailbox, type the contact's email address in the check names field then click the check names button. Click OK.
- In Do the following, select Redirect to.
- Once again, if the display name is unique, select it and click Add, otherwise type the address in the check names field and click check names. Click OK.
- Click Save to save the rule and close the dialog. (More Options has additional options such as stop processing more rules.)
Messages sent to the contact address are now being delivered to the user's mailbox. The mailbox user won't be able to reply using the contact address until they are given Send As permission.
If you prefer using PowerShell, the cmdlet is
New-TransportRule -Name "rule name" -SentTo firstname.lastname@example.org -RedirectMessageTo email@example.com -Mode Enforce
More information on transport rules and conditions is available at Transport Rules
Step 3: Assign Send As Permission
You need to use PowerShell to assign send as permission to a contact. Log into Exchange using PowerShell and run the Add-RecipientPermission cmdlet, giving the mailbox user Send As permission on the contact. You can use the display name, alias, or email address in the contact and trustee fields. If the display names are not unique, use the email address.
Add-RecipientPermission "contact alias" -AccessRights SendAs -Trustee "mailbox alias"
To hide the contact in the address list so other users don't select it by mistake, use
Set-MailContact firstname.lastname@example.org -HiddenFromAddressListsEnabled $true
You can send as the contact by typing the email address (or display name, if unique) in the From field.
Using the address to send email
When you are using Outlook on the desktop and want to send from the address, select the distribution group name or contact in the From field. The first time you use it, you’ll need to select From < Another Email address and select your group or contact name. It can take up to 24 hours for the Offline address book to update, but it will be listed under All Groups or All Contacts immediately.
After the first use, the address will be listed under the From menu.
Outlook Web Access users can change the From address.
- First Show the From field by clicking on the 3 dots and choosing Show From.
- Right click on your address in the From field and choose Remove.
- Start typing in the address or display name of the Distribution Group, User Contact, or mailbox you have Send as rights on and select it when it comes up.
You can create single member distribution groups in any version of Exchange server, however the screenshots and exact steps will vary in each version.