{"id":15552,"date":"2026-03-24T09:02:24","date_gmt":"2026-03-24T00:02:24","guid":{"rendered":"https:\/\/m365jp.net\/?p=15552"},"modified":"2026-03-24T09:06:55","modified_gmt":"2026-03-24T00:06:55","slug":"mc1259820-offline-attachments-policy-for-the-new-outlook-for-windows","status":"publish","type":"post","link":"https:\/\/m365jp.net\/index.php\/2026-03-24-mc1259820-offline-attachments-policy-for-the-new-outlook-for-windows","title":{"rendered":"MC1259820 | Offline attachments policy for the new Outlook for Windows"},"content":{"rendered":"<div class=\"postie-post\">\n<div>\n<hr>\n<table id=\"section\">\n<tbody>\n<tr>\n<th width=\"95%\">MC1259820 | Offline attachments policy for the new Outlook for Windows<\/th>\n<\/tr>\n<\/tbody>\n<\/table>\n<hr>\n<table id=\"data\">\n<tbody>\n<tr>\n<th>Classification<\/th>\n<td>stayInformed<\/td>\n<\/tr>\n<tr>\n<th>Last Updated<\/th>\n<td>03\/23\/2026 23:27:01<\/td>\n<\/tr>\n<tr>\n<th>Start Time<\/th>\n<td>03\/23\/2026 23:26:52<\/td>\n<\/tr>\n<tr>\n<th>End Time<\/th>\n<td>05\/17\/2026 07:00:00<\/td>\n<\/tr>\n<tr>\n<th>Message Content<\/th>\n<td>\n<p><b>[Introduction]<\/b><\/p>\n<p>  <\/p>\n<p>We are introducing a new <code>OWAMailboxPolicy<\/code> setting that allows administrators to control whether file attachments are available when users work offline in the new Outlook for Windows. This change adds a tenant-level configuration option for managing   offline attachment access while preserving existing offline policy behavior by default.<\/p>\n<p><b>[When this will happen:]<\/b><\/p>\n<p>  <\/p>\n<p>The new policy will rollout <b>mid-April 2026<\/b><\/p>\n<p><b>[How this affects your organization:]<\/b><\/p>\n<p><b>Who is affected:<\/b><\/p>\n<p>  <\/p>\n<ul>  <\/p>\n<li>Exchange Online administrators<\/li>\n<p>  <\/p>\n<li>Users of the new Outlook for Windows who use Offline mode<\/li>\n<p>  <\/ul>\n<p><b>What will happen:<\/b><\/p>\n<p>  <\/p>\n<ul>  <\/p>\n<li>A new <code>OWAMailboxPolicy<\/code> setting named <code>AttachmentsOfflineEnabledWin<\/code> becomes available.<\/li>\n<p>  <\/p>\n<li>The policy is <b>enabled by default<\/b> (<code>$true<\/code>).<\/li>\n<p>  <\/p>\n<li>Administrators can allow or block access to file attachments while working offline in the new Outlook for Windows.<\/li>\n<p>  <\/p>\n<li>This change does not affect the existing configuration of <code>OfflineEnabledWin<\/code>.<\/li>\n<p>  <\/p>\n<li>If <code>OfflineEnabledWin<\/code> is set to <code>$false<\/code>, offline file attachments remain disabled even if  <code>AttachmentsOfflineEnabledWin<\/code> is set to <code>$true<\/code>.<\/li>\n<p>  <\/ul>\n<table border=\"1\" cellpadding=\"6\" cellspacing=\"0\">  <\/p>\n<tbody>\n<tr>  <\/p>\n<th>OfflineEnabledWin<\/th>\n<p>  <\/p>\n<th>AttachmentsOfflineEnabledWin<\/th>\n<p>  <\/p>\n<th>Offline mail available?<\/th>\n<p>  <\/p>\n<th>Offline attachments available?<\/th>\n<p>  <\/p>\n<th>Description<\/th>\n<p>  <\/tr>\n<p>  <\/p>\n<tr>  <\/p>\n<td>true<\/td>\n<p>  <\/p>\n<td>true<\/td>\n<p>  <\/p>\n<td>Yes<\/td>\n<p>  <\/p>\n<td>Yes<\/td>\n<p>  <\/p>\n<td>Offline mode is enabled. Users can work offline and access file attachments.<\/td>\n<p>  <\/tr>\n<p>  <\/p>\n<tr>  <\/p>\n<td>true<\/td>\n<p>  <\/p>\n<td>false<\/td>\n<p>  <\/p>\n<td>Yes<\/td>\n<p>  <\/p>\n<td>No<\/td>\n<p>  <\/p>\n<td>Offline mode is enabled, but file attachments are not accessible while offline.<\/td>\n<p>  <\/tr>\n<p>  <\/p>\n<tr>  <\/p>\n<td>false<\/td>\n<p>  <\/p>\n<td>true<\/td>\n<p>  <\/p>\n<td>No<\/td>\n<p>  <\/p>\n<td>No<\/td>\n<p>  <\/p>\n<td>Offline mode is disabled. File attachments are also not available while offline.<\/td>\n<p>  <\/tr>\n<p>  <\/p>\n<tr>  <\/p>\n<td>false<\/td>\n<p>  <\/p>\n<td>false<\/td>\n<p>  <\/p>\n<td>No<\/td>\n<p>  <\/p>\n<td>No<\/td>\n<p>  <\/p>\n<td>Offline mode is fully disabled. No offline mail or attachments are available.<\/td>\n<p>  <\/tr>\n<p>  <\/tbody>\n<\/table>\n<p>  <\/p>\n<p><b>[What you can do to prepare:]<\/b><\/p>\n<p>  <\/p>\n<ul>  <\/p>\n<li>No action is required if the default behavior meets your organization\u2019s requirements.<\/li>\n<p>  <\/p>\n<li>Review your existing <code>OfflineEnabledWin<\/code> policy configuration.<\/li>\n<p>  <\/p>\n<li>Configure <code>AttachmentsOfflineEnabledWin<\/code> at the tenant level if you want to control offline attachment access.<\/li>\n<p>  <\/p>\n<li>Communicate any changes to helpdesk or security teams.<\/li>\n<p>  <\/ul>\n<p>Learn more and configure the policy using Exchange PowerShell: <br \/>  <a href=\"https:\/\/learn.microsoft.com\/powershell\/module\/exchangepowershell\/set-owamailboxpolicy?view=exchange-ps\">Set-OwaMailboxPolicy documentation<\/a>.<\/p>\n<ul>  <\/ul>\n<p><b>[Compliance considerations:]<\/b><\/p>\n<p>  <\/p>\n<p>No compliance considerations identified, review as appropriate for your organization.<\/p>\n<\/td>\n<\/tr>\n<tr>\n<th>Machine Translation<\/th>\n<td>\n<p><b>[\u306f\u3058\u3081\u306b]<\/b><\/p>\n<p>  <\/p>\n<p>\u65b0\u3057\u3044Outlook for Windows\u3067\u30e6\u30fc\u30b6\u30fc\u304c\u30aa\u30d5\u30e9\u30a4\u30f3\u4f5c\u696d\u4e2d\u306b\u30d5\u30a1\u30a4\u30eb\u6dfb\u4ed8\u30d5\u30a1\u30a4\u30eb\u304c\u5229\u7528\u53ef\u80fd\u304b\u3069\u3046\u304b\u3092\u7ba1\u7406\u8005\u304c\u7ba1\u7406\u3067\u304d\u308b\u65b0\u3057\u3044 <code>OWAMailboxPolicy<\/code> \u8a2d\u5b9a\u3092\u5c0e\u5165\u3057\u307e\u3059\u3002\u3053\u306e\u5909\u66f4\u306b\u3088\u308a\u3001\u65e2\u5b58\u306e\u30aa\u30d5\u30e9\u30a4\u30f3\u30dd\u30ea\u30b7\u30fc\u306e\u52d5\u4f5c\u3092\u30c7\u30d5\u30a9\u30eb\u30c8\u3067\u7dad\u6301\u3057\u3064\u3064\u3001\u30aa\u30d5\u30e9\u30a4\u30f3\u306e\u6dfb\u7f6e\u30a2\u30af\u30bb\u30b9\u3092\u7ba1\u7406\u3059\u308b\u30c6\u30ca\u30f3\u30c8\u30ec\u30d9\u30eb\u306e\u8a2d\u5b9a\u30aa\u30d7\u30b7\u30e7\u30f3\u304c\u8ffd\u52a0\u3055\u308c\u307e\u3059\u3002<\/p>\n<p><b>[\u3044\u3064\u8d77\u3053\u308b\u304b:]<\/b><\/p>\n<p>  <\/p>\n<p>\u65b0\u65b9\u91dd\u306f<b>2026\u5e744\u6708\u4e2d\u65ec\u306b<\/b>\u5c55\u958b\u3055\u308c\u307e\u3059<\/p>\n<p><b>[\u3053\u308c\u304c\u3042\u306a\u305f\u306e\u7d44\u7e54\u306b\u3069\u306e\u3088\u3046\u306a\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u304b:]<\/b><\/p>\n<p><b>\u5f71\u97ff\u3092\u53d7\u3051\u308b\u4eba\u7269:<\/b><\/p>\n<p>  <\/p>\n<ul>  <\/p>\n<li>Exchange Online\u7ba1\u7406\u8005<\/li>\n<p>  <\/p>\n<li>\u30aa\u30d5\u30e9\u30a4\u30f3\u30e2\u30fc\u30c9\u3092\u4f7f\u7528\u3059\u308b\u65b0\u3057\u3044Outlook\u306eWindows\u30e6\u30fc\u30b6\u30fc<\/li>\n<p>  <\/ul>\n<p><b>\u4eca\u5f8c\u306e\u5c55\u958b:<\/b><\/p>\n<p>  <\/p>\n<ul>  <\/p>\n<li>\u65b0\u3057\u3044 <code>OWAMailboxPolicy<\/code> \u8a2d\u5b9a\u300c <code>AttachmentsOfflineEnabledWin<\/code> \u300d\u304c\u5229\u7528\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002<\/li>\n<p>  <\/p>\n<li>\u3053\u306e\u30dd\u30ea\u30b7\u30fc\u306f <b>\u30c7\u30d5\u30a9\u30eb\u30c8\u3067\u6709\u52b9<\/b> \u5316\u3055\u308c\u3066\u3044\u307e\u3059(<code>$true<\/code>)\u3002<\/li>\n<p>  <\/p>\n<li>\u7ba1\u7406\u8005\u306f\u3001\u65b0\u3057\u3044Outlook(Windows\u7248)\u3067\u30aa\u30d5\u30e9\u30a4\u30f3\u4f5c\u696d\u4e2d\u306b\u30d5\u30a1\u30a4\u30eb\u6dfb\u4ed8\u30d5\u30a1\u30a4\u30eb\u3078\u306e\u30a2\u30af\u30bb\u30b9\u3092\u8a31\u53ef\u307e\u305f\u306f\u30d6\u30ed\u30c3\u30af\u3067\u304d\u307e\u3059\u3002<\/li>\n<p>  <\/p>\n<li>\u3053\u306e\u5909\u66f4\u306f\u65e2\u5b58\u306e <code>OfflineEnabledWin<\/code> \u69cb\u6210\u306b\u306f\u5f71\u97ff\u3057\u307e\u305b\u3093\u3002<\/li>\n<p>  <\/p>\n<li><code>OfflineEnabledWin<\/code>\u304c<code>$false<\/code>\u306b\u8a2d\u5b9a\u3055\u308c\u3066\u3044\u308b\u5834\u5408\u3001<code>$true<\/code>\u306b\u8a2d\u5b9a\u3055\u308c\u3066\u3044\u3066\u3082\u30aa\u30d5\u30e9\u30a4\u30f3\u30d5\u30a1\u30a4\u30eb\u306e\u6dfb\u4ed8\u30d5\u30a1\u30a4\u30eb\u306f\u7121\u52b9<code>AttachmentsOfflineEnabledWin<\/code>\u306e\u307e\u307e\u3067\u3059\u3002<\/li>\n<p>  <\/ul>\n<table border=\"1\" cellpadding=\"6\" cellspacing=\"0\">  <\/p>\n<tbody>\n<tr>  <\/p>\n<th>\u30aa\u30d5\u30e9\u30a4\u30f3EnabledWin<\/th>\n<p>  <\/p>\n<th>AttachmentsOfflineEnabledWin<\/th>\n<p>  <\/p>\n<th>\u30aa\u30d5\u30e9\u30a4\u30f3\u30e1\u30fc\u30eb\u306f\u5229\u7528\u53ef\u80fd\u3067\u3059\u304b?<\/th>\n<p>  <\/p>\n<th>\u30aa\u30d5\u30e9\u30a4\u30f3\u306e\u6dfb\u4ed8\u30d5\u30a1\u30a4\u30eb\u306f\u3042\u308a\u307e\u3059\u304b?<\/th>\n<p>  <\/p>\n<th>\u6982\u8981<\/th>\n<p>  <\/tr>\n<p>  <\/p>\n<tr>  <\/p>\n<td>\u78ba\u304b\u306b<\/td>\n<p>  <\/p>\n<td>\u78ba\u304b\u306b<\/td>\n<p>  <\/p>\n<td>\u306f\u3044<\/td>\n<p>  <\/p>\n<td>\u306f\u3044<\/td>\n<p>  <\/p>\n<td>\u30aa\u30d5\u30e9\u30a4\u30f3\u30e2\u30fc\u30c9\u306f\u6709\u52b9\u3067\u3059\u3002\u30e6\u30fc\u30b6\u30fc\u306f\u30aa\u30d5\u30e9\u30a4\u30f3\u3067\u4f5c\u696d\u3057\u3001\u30d5\u30a1\u30a4\u30eb\u306e\u6dfb\u4ed8\u30d5\u30a1\u30a4\u30eb\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u307e\u3059\u3002<\/td>\n<p>  <\/tr>\n<p>  <\/p>\n<tr>  <\/p>\n<td>\u78ba\u304b\u306b<\/td>\n<p>  <\/p>\n<td>\u507d\u308a<\/td>\n<p>  <\/p>\n<td>\u306f\u3044<\/td>\n<p>  <\/p>\n<td>\u3044\u3044\u3048<\/td>\n<p>  <\/p>\n<td>\u30aa\u30d5\u30e9\u30a4\u30f3\u30e2\u30fc\u30c9\u306f\u6709\u52b9\u3067\u3059\u304c\u3001\u30aa\u30d5\u30e9\u30a4\u30f3\u4e2d\u306f\u30d5\u30a1\u30a4\u30eb\u306e\u6dfb\u4ed8\u30d5\u30a1\u30a4\u30eb\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u307e\u305b\u3093\u3002<\/td>\n<p>  <\/tr>\n<p>  <\/p>\n<tr>  <\/p>\n<td>\u507d\u308a<\/td>\n<p>  <\/p>\n<td>\u78ba\u304b\u306b<\/td>\n<p>  <\/p>\n<td>\u3044\u3044\u3048<\/td>\n<p>  <\/p>\n<td>\u3044\u3044\u3048<\/td>\n<p>  <\/p>\n<td>\u30aa\u30d5\u30e9\u30a4\u30f3\u30e2\u30fc\u30c9\u306f\u7121\u52b9\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002\u30d5\u30a1\u30a4\u30eb\u6dfb\u4ed8\u30d5\u30a1\u30a4\u30eb\u3082\u30aa\u30d5\u30e9\u30a4\u30f3\u3067\u306f\u5229\u7528\u3067\u304d\u307e\u305b\u3093\u3002<\/td>\n<p>  <\/tr>\n<p>  <\/p>\n<tr>  <\/p>\n<td>\u507d\u308a<\/td>\n<p>  <\/p>\n<td>\u507d\u308a<\/td>\n<p>  <\/p>\n<td>\u3044\u3044\u3048<\/td>\n<p>  <\/p>\n<td>\u3044\u3044\u3048<\/td>\n<p>  <\/p>\n<td>\u30aa\u30d5\u30e9\u30a4\u30f3\u30e2\u30fc\u30c9\u306f\u5b8c\u5168\u306b\u7121\u52b9\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002\u30aa\u30d5\u30e9\u30a4\u30f3\u306e\u30e1\u30fc\u30eb\u3084\u6dfb\u4ed8\u30d5\u30a1\u30a4\u30eb\u306f\u5229\u7528\u3067\u304d\u307e\u305b\u3093\u3002<\/td>\n<p>  <\/tr>\n<p>  <\/tbody>\n<\/table>\n<p>  <\/p>\n<p><b>[\u6e96\u5099\u306e\u305f\u3081\u306b\u3067\u304d\u308b\u3053\u3068:]<\/b><\/p>\n<p>  <\/p>\n<ul>  <\/p>\n<li>\u30c7\u30d5\u30a9\u30eb\u30c8\u306e\u52d5\u4f5c\u304c\u7d44\u7e54\u306e\u8981\u4ef6\u3092\u6e80\u305f\u3057\u3066\u3044\u308c\u3070\u3001\u4f55\u306e\u30a2\u30af\u30b7\u30e7\u30f3\u3082\u5fc5\u8981\u3042\u308a\u307e\u305b\u3093\u3002<\/li>\n<p>  <\/p>\n<li>\u65e2\u5b58\u306e <code>OfflineEnabledWin<\/code> \u30dd\u30ea\u30b7\u30fc\u8a2d\u5b9a\u3092\u898b\u76f4\u3057\u307e\u3057\u3087\u3046\u3002<\/li>\n<p>  <\/p>\n<li>\u30aa\u30d5\u30e9\u30a4\u30f3\u306e\u6dfb\u4ed8\u30d5\u30a1\u30a4\u30eb\u30a2\u30af\u30bb\u30b9\u3092\u5236\u5fa1\u3057\u305f\u3044\u5834\u5408\u306f\u3001\u30c6\u30ca\u30f3\u30c8\u30ec\u30d9\u30eb\u3067 <code>AttachmentsOfflineEnabledWin<\/code> \u3092\u8a2d\u5b9a\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/li>\n<p>  <\/p>\n<li>\u5909\u66f4\u304c\u3042\u308c\u3070\u30d8\u30eb\u30d7\u30c7\u30b9\u30af\u3084\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u30c1\u30fc\u30e0\u306b\u4f1d\u3048\u307e\u3057\u3087\u3046\u3002<\/li>\n<p>  <\/ul>\n<p>\u8a73\u3057\u304f\u306f\u3001Exchange PowerShell\u3092\u4f7f\u3063\u3066\u30dd\u30ea\u30b7\u30fc\u3092\u8a2d\u5b9a\u3057\u3066\u304f\u3060\u3055\u3044:<br \/>  <a href=\"https:\/\/learn.microsoft.com\/powershell\/module\/exchangepowershell\/set-owamailboxpolicy?view=exchange-ps\">Set-OwaMailboxPolicy\u306e\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8<\/a>\u3002<\/p>\n<ul>  <\/ul>\n<p><b>[\u30b3\u30f3\u30d7\u30e9\u30a4\u30a2\u30f3\u30b9\u4e0a\u306e\u8003\u616e\u4e8b\u9805:]<\/b><\/p>\n<p>  <\/p>\n<p>\u30b3\u30f3\u30d7\u30e9\u30a4\u30a2\u30f3\u30b9\u4e0a\u306e\u61f8\u5ff5\u4e8b\u9805\u306f\u7279\u5b9a\u3055\u308c\u305a\u3001\u7d44\u7e54\u306b\u5fdc\u3058\u3066\u30ec\u30d3\u30e5\u30fc\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>MC1259820 | Offline attachments policy for the new Outlook for Windows Classification stayInformed Last Update [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-15552","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/15552","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/comments?post=15552"}],"version-history":[{"count":0,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/15552\/revisions"}],"wp:attachment":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/media?parent=15552"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/categories?post=15552"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/tags?post=15552"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}