Office 365 notification MC224531 (October 19) came as a surprise because who could have known that site mailboxes are still around? After all, in January 2017, Microsoft announced their intention to block the creation of new site mailboxes. Nearly four years later, you might think that organizations had figured out how to dump these unfortunate creations.
The History of Site Mailboxes
Site mailboxes came about in a Microsoft effort to show that Exchange 2013 and SharePoint 2013 could work together to deliver value. In on-premises environments, the long checklist of steps needed to bring the two servers together put many off.
Figure 1: Site Mailboxes (image credit: Microsoft)
Things were much easier inside Office 365 where Microsoft took care of the configuration. Even so, site mailboxes were obsoleted by developments soon after they were released with the advent of Office 365 Groups (now Microsoft 365 Groups). Since Office 365 Groups came along, we’ve seen an increasing amount of integration across the Microsoft 365 ecosystem encouraged by the availability of a common platform (the substrate) and common Graph APIs.
In any case, the final curtain for site mailboxes descends in April 2021. Microsoft says that they will retire site mailboxes at that point.
If Your Tenant Has Site Mailboxes
If you didn’t receive the notification, Microsoft hasn’t found any site mailboxes in your tenant and you have nothing to worry about. Following Microsoft’s advice, I looked to see what site mailboxes existed and found three were present:
# Find details of site mailboxes known to the tenant
Get-SiteMailbox -BypassOwnerCheck -ResultSize Unlimited | Format-List Name, WhenCreated, SharePointUrl, Owners
Name : SMO-Office365forExchangeProfessionals
WhenCreated : 02/01/2015 10:33:33
SharePointUrl : https://office365itpros.sharepoint.com/O365Book
Owners : {TRedmond, Ben Owens, Kim Akers}
Name : O365-ExchangeConnections2015
WhenCreated : 16/02/2015 11:22:14
SharePointUrl : https:// office365itpros.sharepoint.com/Exchange Connections 2015
Owners : {TRedmond}
Name : SMO-Projects
WhenCreated : 27/01/2014 20:36:50
SharePointUrl : https:// office365itpros.sharepoint.com/Projects
Owners : {TRedmond}
All the site mailboxes date from 2014-2015, right around the time when we first started working on the Office 365 for IT Pros book (the first two versions were called Office 365 for Exchange Professionals). Microsoft launched Office 365 Groups in November 2014 and we switched to Groups soon afterwards.
No trace of the SharePoint sites could be found. They might have been removed in the past during a purge of inactive sites. If the sites were available, their content could be retrieved using Office 365 content searches and exported (Microsoft has a script to do the job on GitHub).
Failure to Clean Up
Site mailboxes don’t really contain any real items. Instead, they hold stubs pointing to documents in SharePoint libraries. The stubs are small, so it’s easy to detect folders used for this purpose because they usually have many items but are quite small. A check of the site mailboxes with Get-ExoMailboxFolderStatistics revealed that there was nothing much in any mailbox:
# Get details of what's in site mailboxes
Get-ExoMailbox -RecipientTypeDetails TeamMailbox | Get-ExoMailboxFolderStatistics | Format-Table Name, ItemsInFolder
Site mailboxes have a recipient type of TeamMailbox because at one time that’s what they were going to be called. Luckily Microsoft changed the name to focus on sites as otherwise they would have had to find a new name for Teams.
In the knowledge that the site mailboxes were useless artefacts of the past, I tried to delete them. Unhappily, the attempt failed with some horrible errors because the linked SharePoint sites couldn’t be found:
Get-ExoMailbox -RecipientTypeDetails TeamMailbox | Remove-Mailbox
WARNING: Site mailbox "O365-ExchangeConnections2015" couldn't be unlinked from the SharePoint site "https://office365itpros.sharepoint.com/Exchange Connections 2015" because of the following error: "SharePoint site "https://office365itpros.sharepoint.com/Exchange%20Connections%202015" couldn't be
contacted because of the following the error: "WebException - Status:ProtocolError; Message:The remote server returned an error: (404) Not Found.;HttpStatusCode:NotFound;HttpStatusDescription:Not
I’m Leaving the Problem to Microsoft
I lost interest at this point. The site mailboxes don’t bother me and I’m sure Microsoft will clean up the mess when they retire site mailboxes next April. After ignoring the trio of site mailboxes for so long, I can wait a little longer. In the meantime, to avoid seeing any further trace of the site mailboxes, I hid them by running:
Others might not be in the same state and need to transition off site mailboxes to Microsoft 365 Groups (the logical choice). If so, follow Microsoft’s advice to export the content from your site mailboxes and let this unsuccessful foray into on-premises server integration fade into the background.
We dropped site mailboxes from the Office 365 for IT Pros eBook in 2016. But we have tons of other great information in the only book which tracks changes across Office 365 and has done so since 2015.
{"id":null,"mode":"button","open_style":"in_modal","currency_code":"EUR","currency_symbol":"\u20ac","currency_type":"decimal","blank_flag_url":"https:\/\/office365itpros.com\/wp-content\/plugins\/tip-jar-wp\/\/assets\/images\/flags\/blank.gif","flag_sprite_url":"https:\/\/office365itpros.com\/wp-content\/plugins\/tip-jar-wp\/\/assets\/images\/flags\/flags.png","default_amount":100,"top_media_type":"featured_image","featured_image_url":"https:\/\/office365itpros.com\/wp-content\/uploads\/2022\/11\/cover-141x200.jpg","featured_embed":"","header_media":null,"file_download_attachment_data":null,"recurring_options_enabled":true,"recurring_options":{"never":{"selected":true,"after_output":"One time only"},"weekly":{"selected":false,"after_output":"Every week"},"monthly":{"selected":false,"after_output":"Every month"},"yearly":{"selected":false,"after_output":"Every year"}},"strings":{"current_user_email":"","current_user_name":"","link_text":"Virtual Tip Jar","complete_payment_button_error_text":"Check info and try again","payment_verb":"Pay","payment_request_label":"Office 365 for IT Pros","form_has_an_error":"Please check and fix the errors above","general_server_error":"Something isn't working right at the moment. Please try again.","form_title":"Office 365 for IT Pros","form_subtitle":null,"currency_search_text":"Country or Currency here","other_payment_option":"Other payment option","manage_payments_button_text":"Manage your payments","thank_you_message":"Thank you for supporting the work of Office 365 for IT Pros!","payment_confirmation_title":"Office 365 for IT Pros","receipt_title":"Your Receipt","print_receipt":"Print Receipt","email_receipt":"Email Receipt","email_receipt_sending":"Sending receipt...","email_receipt_success":"Email receipt successfully sent","email_receipt_failed":"Email receipt failed to send. Please try again.","receipt_payee":"Paid to","receipt_statement_descriptor":"This will show up on your statement as","receipt_date":"Date","receipt_transaction_id":"Transaction ID","receipt_transaction_amount":"Amount","refund_payer":"Refund from","login":"Log in to manage your payments","manage_payments":"Manage Payments","transactions_title":"Your Transactions","transaction_title":"Transaction Receipt","transaction_period":"Plan Period","arrangements_title":"Your Plans","arrangement_title":"Manage Plan","arrangement_details":"Plan Details","arrangement_id_title":"Plan ID","arrangement_payment_method_title":"Payment Method","arrangement_amount_title":"Plan Amount","arrangement_renewal_title":"Next renewal date","arrangement_action_cancel":"Cancel Plan","arrangement_action_cant_cancel":"Cancelling is currently not available.","arrangement_action_cancel_double":"Are you sure you'd like to cancel?","arrangement_cancelling":"Cancelling Plan...","arrangement_cancelled":"Plan Cancelled","arrangement_failed_to_cancel":"Failed to cancel plan","back_to_plans":"\u2190 Back to Plans","update_payment_method_verb":"Update","sca_auth_description":"Your have a pending renewal payment which requires authorization.","sca_auth_verb":"Authorize renewal payment","sca_authing_verb":"Authorizing payment","sca_authed_verb":"Payment successfully authorized!","sca_auth_failed":"Unable to authorize! Please try again.","login_button_text":"Log in","login_form_has_an_error":"Please check and fix the errors above","uppercase_search":"Search","lowercase_search":"search","uppercase_page":"Page","lowercase_page":"page","uppercase_items":"Items","lowercase_items":"items","uppercase_per":"Per","lowercase_per":"per","uppercase_of":"Of","lowercase_of":"of","back":"Back to plans","zip_code_placeholder":"Zip\/Postal Code","download_file_button_text":"Download File","input_field_instructions":{"tip_amount":{"placeholder_text":"How much would you like to tip?","initial":{"instruction_type":"normal","instruction_message":"How much would you like to tip? Choose any currency."},"empty":{"instruction_type":"error","instruction_message":"How much would you like to tip? Choose any currency."},"invalid_curency":{"instruction_type":"error","instruction_message":"Please choose a valid currency."}},"recurring":{"placeholder_text":"Recurring","initial":{"instruction_type":"normal","instruction_message":"How often would you like to give this?"},"success":{"instruction_type":"success","instruction_message":"How often would you like to give this?"},"empty":{"instruction_type":"error","instruction_message":"How often would you like to give this?"}},"name":{"placeholder_text":"Name on Credit Card","initial":{"instruction_type":"normal","instruction_message":"Enter the name on your card."},"success":{"instruction_type":"success","instruction_message":"Enter the name on your card."},"empty":{"instruction_type":"error","instruction_message":"Please enter the name on your card."}},"privacy_policy":{"terms_title":"Terms and conditions","terms_body":null,"terms_show_text":"View Terms","terms_hide_text":"Hide Terms","initial":{"instruction_type":"normal","instruction_message":"I agree to the terms."},"unchecked":{"instruction_type":"error","instruction_message":"Please agree to the terms."},"checked":{"instruction_type":"success","instruction_message":"I agree to the terms."}},"email":{"placeholder_text":"Your email address","initial":{"instruction_type":"normal","instruction_message":"Enter your email address"},"success":{"instruction_type":"success","instruction_message":"Enter your email address"},"blank":{"instruction_type":"error","instruction_message":"Enter your email address"},"not_an_email_address":{"instruction_type":"error","instruction_message":"Make sure you have entered a valid email address"}},"note_with_tip":{"placeholder_text":"Your note here...","initial":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"empty":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"not_empty_initial":{"instruction_type":"normal","instruction_message":"Attach a note to your tip (optional)"},"saving":{"instruction_type":"normal","instruction_message":"Saving note..."},"success":{"instruction_type":"success","instruction_message":"Note successfully saved!"},"error":{"instruction_type":"error","instruction_message":"Unable to save note note at this time. Please try again."}},"email_for_login_code":{"placeholder_text":"Your email address","initial":{"instruction_type":"normal","instruction_message":"Enter your email to log in."},"success":{"instruction_type":"success","instruction_message":"Enter your email to log in."},"blank":{"instruction_type":"error","instruction_message":"Enter your email to log in."},"empty":{"instruction_type":"error","instruction_message":"Enter your email to log in."}},"login_code":{"initial":{"instruction_type":"normal","instruction_message":"Check your email and enter the login code."},"success":{"instruction_type":"success","instruction_message":"Check your email and enter the login code."},"blank":{"instruction_type":"error","instruction_message":"Check your email and enter the login code."},"empty":{"instruction_type":"error","instruction_message":"Check your email and enter the login code."}},"stripe_all_in_one":{"initial":{"instruction_type":"normal","instruction_message":"Enter your credit card details here."},"empty":{"instruction_type":"error","instruction_message":"Enter your credit card details here."},"success":{"instruction_type":"normal","instruction_message":"Enter your credit card details here."},"invalid_number":{"instruction_type":"error","instruction_message":"The card number is not a valid credit card number."},"invalid_expiry_month":{"instruction_type":"error","instruction_message":"The card's expiration month is invalid."},"invalid_expiry_year":{"instruction_type":"error","instruction_message":"The card's expiration year is invalid."},"invalid_cvc":{"instruction_type":"error","instruction_message":"The card's security code is invalid."},"incorrect_number":{"instruction_type":"error","instruction_message":"The card number is incorrect."},"incomplete_number":{"instruction_type":"error","instruction_message":"The card number is incomplete."},"incomplete_cvc":{"instruction_type":"error","instruction_message":"The card's security code is incomplete."},"incomplete_expiry":{"instruction_type":"error","instruction_message":"The card's expiration date is incomplete."},"incomplete_zip":{"instruction_type":"error","instruction_message":"The card's zip code is incomplete."},"expired_card":{"instruction_type":"error","instruction_message":"The card has expired."},"incorrect_cvc":{"instruction_type":"error","instruction_message":"The card's security code is incorrect."},"incorrect_zip":{"instruction_type":"error","instruction_message":"The card's zip code failed validation."},"invalid_expiry_year_past":{"instruction_type":"error","instruction_message":"The card's expiration year is in the past"},"card_declined":{"instruction_type":"error","instruction_message":"The card was declined."},"missing":{"instruction_type":"error","instruction_message":"There is no card on a customer that is being charged."},"processing_error":{"instruction_type":"error","instruction_message":"An error occurred while processing the card."},"invalid_request_error":{"instruction_type":"error","instruction_message":"Unable to process this payment, please try again or use alternative method."},"invalid_sofort_country":{"instruction_type":"error","instruction_message":"The billing country is not accepted by SOFORT. Please try another country."}}}},"fetched_oembed_html":false}
I believe the Message ID referenced above is wrong. I see MC224531 in one of my tenants.