Knowledge Base

KB5005: Multiple Email Accounts in Outlook

Configuring multiple email accounts in Outlook stores sent mail in the primary account only which may have implications for archiving and information security

If you are considering configuring more than one email account in Microsoft Outlook it is important to understand how sent mail is treated for additional accounts.

Since Outlook 2000 it is not possible to have more than once instance of Outlook running and so not possible to have separate email accounts displaying in separate Outlook windows running simultaneously.

To configure multiple email accounts with Microsoft Outlook there are two practical solutions …

Create a separate *profile* for each mailbox.

Only one profile can be opened at a time so to switch between the profiles requires closing and opening Outlook. Perhaps not the most convenient method but ensures each account functions as a primary account. This would suit additional accounts that require occassional or infrequent monitoring.

Configure Outlook to receive mail for multiple accounts.

This is the most obvious choice but there is a caveat. When sending or replying to email in any account only the primary mailbox is used to send mail and the message is stored only in the primary accounts mailbox.

This can lead to confusion and potential information loss as the complete conversation is not recorded in additional mail accounts.

Consider the following behaviour if multiple accounts are configured in Outlook

Example Configuration

Using the following example configuration of email accounts, the outcome of sending and replying are demonstrated below

  • primary@ is setup as the first and primary mailbox
  • secondary@  is setup as the secondary mailbox
  • tertiary@ is setup as the third mailbox

Outcomes  (based on example configuration)

 All Inbound mail delivers to and is stored in the correct account

When sending ...

Sending mail from primary@ stores sent items in the primary@ mailbox

Sending mail from secondary@ stores sent items in the primary@ mailbox

Sending mail from tertiary@ stores sent items in the primary@ mailbox

When replying ...

Replies from primary@ stores sent items in the primary@ mailbox

Replies from secondary@ stores sent items in the primary@ mailbox

Replies from tertiary@ stores sent items in the primary@ mailbox

So as you can see, sent mail does not send from nor get stored in any other account beyond the primary account. This could lead to confusion. Note that recipient does see the correct sending / reply-to address.

How could this be a problem? Aside from incomplete email conversations in the additional mailboxes consider the following scenario -  you are a business owner and operate two accounts in Outlook as follows ...

* sales@yourbusiness - perhaps shared with a team for sales enquiries and set up as the primary mailbox

* accounts@yourbusiness - a commercial in confidence account used for running the business and setup as the secondary

If you were to send payslips to your employees from accounts@ it would display to the recipients as accounts@ however the mail would be sent by and stored in the sales@ mailbox. Down the track you hire a sales person and share the mailbox to find you've got email of a confidential nature that you didn't intend to reside in the sales@ mailbox.

As long as these outcomes are acceptable and understood multiple  accounts can be configured within the one Outlook profile.


This article is intended for Microsoft Outlook for Windows and the sending behaviour for additional accounts may not apply for Outlook for Mac, Android or IOS. The sending behaviour is the same for both O365 and GSuite email accounts (using GSuite Sync for Outlook).

Setting up additional email accounts as POP or IMAP is a possible solution however we would argue that this is not an acceptable outcome given reduced functionality and the absence of syncing for peripheral services such as contacts and calendars.

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