Microsoft Office 365, along with the Microsoft Exchange range of products going back years and years, has always allowed mailboxes and users to have a range of alias in addition to their primary email address. However, until now, you could not send an email out using one of those addresses.

Proxy addresses provide additional email addresses and might be employed for many good reasons - for example, to provide variations of your email address, including catching common misspellings. Or, your organisation might have multiple domains and brands, and you have an email address for each domain.

Whatever the case, the fact remained you could receive an email to many different email addresses, but could not send as any of these except the single primary email address assigned to you.

Office 365 administrators know too well how many times they have been asked how to allow someone to email as one of their alternate email addresses.

To date, the only solutions were third-party products and workarounds. One such workaround is to make a shared mailbox, assign the user as having full access, and send-as access, to the mailbox, allocate it one of the proxy addresses instead of the user, and then set email forwarding on the mailbox to the user.

Happily, Microsoft has made this work. Originally, the feature was slated for release in June, but has come early and while it may not yet be rolled out to every Office 365 tenancy most Office 365 customers should find they now have this feature.

The one catch is it's not enabled by default. It's quickly switched on with PowerShell, enabling the ‘SendFromAlias’ feature, with this command:

Set-OrganizationConfig -SendFromAliasEnabled $True

If you have not previously used PowerShell to administer Office 365 here’s a helpful site to get you going.

Once turned on, your users can compose a new email and will find they have the option to select “Other email addresses” by clicking the “From:” button. (If you don’t see this, ensure you have turned on “Show From”.)

Enter the proxy address you wish to use, and compose and send the email. Outlook will remember the address and present it inside the From: list for future use without needing to type it in.

Do yourself and your users a favour: turn this oft-requested feature on today.