Multiple Services :: Delayed Delivery to Microsoft 365

Update timeline

1. investigating Sep 04, 2026, 09:06 AM UTC

   Due to an outage within Microsoft Exchange Online and Microsoft 365 we are currently experiencing delays in email delivery to relays as *mail.protection.outlook.com used by Microsoft 365, Exchange Online etc. Affected are currently all services sending e-mails to said domains. We will keep you updated. Back to current status Status History Subscribe to receive status updates by email Close Subscribe Manage Subscription Manage Existing Subscription Create New Subscription Subscribe to receive status updates by text message Afghanistan [+93] Aland Islands [+358] Albania [+355] Algeria [+213] AmericanSamoa [+1 684] Andorra [+376] Angola [+244] Anguilla [+1 264] Antarctica [+672] Antigua and Barbuda [+1268] Argentina [+54] Armenia [+374] Aruba [+297] Australia [+61] Austria [+43] Azerbaijan [+994] Bahamas [+1 242] Bahrain [+973] Bangladesh [+880] Barbados [+1 246] Belarus [+375] Belgium [+32] Belize [+501] Benin [+229] Bermuda [+1 441] Bhutan [+975] Bolivia, Plurinational State of [+591] Bosnia and Herzegovina [+387] Botswana [+267] Brazil [+55] British Indian Ocean Territory [+246] Brunei Darussalam [+673] Bulgaria [+359] Burkina Faso [+226] Burundi [+257] Cambodia [+855] Cameroon [+237] Canada [+1] Cape Verde [+238] Cayman Islands [+ 345] Central African Republic [+236] Chad [+235] Chile [+56] China [+86] Christmas Island [+61] Cocos (Keeling) Islands [+61] Colombia [+57] Comoros [+269] Congo [+242] Congo, The Democratic Republic of the [+243] Cook Islands [+682] Costa Rica [+506] Cote d'Ivoire [+225] Croatia [+385] Cuba [+53] Cyprus [+537] Czech Republic [+420] Denmark [+45] Djibouti [+253] Dominica [+1 767] Dominican Republic [+1 849] Ecuador [+593] Egypt [+20] El Salvador [+503] Equatorial Guinea [+240] Eritrea [+291] Estonia [+372] Ethiopia [+251] Falkland Islands (Malvinas) [+500] Faroe Islands [+298] Fiji [+679] Finland [+358] France [+33] French Guiana [+594] French Polynesia [+689] Gabon [+241] Gambia [+220] Georgia [+995] Germany [+49] Ghana [+233] Gibraltar [+350] Greece [+30] Greenland [+299] Grenada [+1 473] Guadeloupe [+590] Guam [+1 671] Guatemala [+502] Guernsey [+44] Guinea [+224] Guinea-Bissau [+245] Guyana [+595] Haiti [+509] Holy See (Vatican City State) [+379] Honduras [+504] Hong Kong [+852] Hungary [+36] Iceland [+354] India [+91] Indonesia [+62] Iran, Islamic Republic of [+98] Iraq [+964] Ireland [+353] Isle of Man [+44] Israel [+972] Italy [+39] Jamaica [+1 876] Japan [+81] Jersey [+44] Jordan [+962] Kazakhstan [+7 7] Kenya [+254] Kiribati [+686] Korea, Democratic People's Republic of [+850] Korea, Republic of [+82] Kuwait [+965] Kyrgyzstan [+996] Lao People's Democratic Republic [+856] Latvia [+371] Lebanon [+961] Lesotho [+266] Liberia [+231] Libyan Arab Jamahiriya [+218] Liechtenstein [+423] Lithuania [+370] Luxembourg [+352] Macao [+853] Macedonia, The Former Yugoslav Republic of [+389] Madagascar [+261] Malawi [+265] Malaysia [+60] Maldives [+960] Mali [+223] Malta [+356] Marshall Islands [+692] Martinique [+596] Mauritania [+222] Mauritius [+230] Mayotte [+262] Mexico [+52] Micronesia, Federated States of [+691] Moldova, Republic of [+373] Monaco [+377] Mongolia [+976] Montenegro [+382] Montserrat [+1664] Morocco [+212] Mozambique [+258] Myanmar [+95] Namibia [+264] Nauru [+674] Nepal [+977] Netherlands [+31] Netherlands Antilles [+599] New Caledonia [+687] New Zealand [+64] Nicaragua [+505] Niger [+227] Nigeria [+234] Niue [+683] Norfolk Island [+672] Northern Mariana Islands [+1 670] Norway [+47] Oman [+968] Pakistan [+92] Palau [+680] Palestinian Territory, Occupied [+970] Panama [+507] Papua New Guinea [+675] Paraguay [+595] Peru [+51] Philippines [+63] Pitcairn [+872] Poland [+48] Portugal [+351] Puerto Rico [+1 939] Qatar [+974] Reunion [+262] Romania [+40] Russia [+7] Rwanda [+250] Saint Barthlemy [+590] Saint Helena, Ascension and Tristan Da Cunha [+290] Saint Kitts and Nevis [+1 869] Saint Lucia [+1 758] Saint Martin [+590] Saint Pierre and Miquelon [+508] Saint Vincent and the Grenadines [+1 784] Samoa [+685] San Marino [+378] Sao Tome and Principe [+239] Saudi Arabia [+966] Senegal [+221] Serbia [+381] Seychelles [+248] Sierra Leone [+232] Singapore [+65] Slovakia [+421] Slovenia [+386] Solomon Islands [+677] Somalia [+252] South Africa [+27] South Georgia and the South Sandwich Islands [+500] Spain [+34] Sri Lanka [+94] Sudan [+249] Suriname [+597] Svalbard and Jan Mayen [+47] Swaziland [+268] Sweden [+46] Switzerland [+41] Syrian Arab Republic [+963] Taiwan, Province of China [+886] Tajikistan [+992] Tanzania, United Republic of [+255] Thailand [+66] Timor-Leste [+670] Togo [+228] Tokelau [+690] Tonga [+676] Trinidad and Tobago [+1 868] Tunisia [+216] Turkey [+90] Turkmenistan [+993] Turks and Caicos Islands [+1 649] Tuvalu [+688] Uganda [+256] Ukraine [+380] United Arab Emirates [+971] United Kingdom [+44] United States [+1] Uruguay [+598] Uzbekistan [+998] Vanuatu [+678] Venezuela, Bolivarian Republic of [+58] Viet Nam [+84] Virgin Islands, British [+1 284] Virgin

2. investigating Sep 04, 2026, 09:06 AM UTC

   Across all data centres., we are currently experiencing delays in email delivery to *mail.protection.outlook.com used by Microsoft 365, Exchange Online etc. Affected are currently all services sending e-mails to said domains. We will keep you updated.

3. identified Sep 04, 2026, 09:09 AM UTC

   Across all data centres we see Microsoft servers temporarily rejecting a large amount of emails with "451 4.7.500 Server busy. Please try again later".

4. identified Sep 04, 2026, 09:09 AM UTC

   Across all data centres we see Microsoft servers temporarily rejecting a large amount of emails with "451 4.7.500 Server busy. Please try again later from".

5. identified Sep 04, 2026, 10:46 AM UTC

   We are monitoring the queuing systems and ensure enough storage to keep queuing messages. Sender might receive Delivery Status Notifications (DSN) in a few cases. In the meantime Microsoft has confirmed the issue: EX1467029 - Users may experience delays receiving email messages from external domains in Exchange Online https://admin.microsoft.com/Adminportal/Home#/servicehealth/history/:/alerts/EX1464935 • Users may experience a delay in receiving email messages from external domains in Exchange Online. • Users may experience intermittent “Server busy” errors, affecting multiple mailboxes. We will keep you updated.

6. identified Sep 04, 2026, 10:46 AM UTC

   We are monitoring the queuing systems and ensure enough storage to keep queuing messages. Sender might receive Delivery Status Notifications (DSN) in a few cases. In the meantime Microsoft has confirmed the issue: EX1467029 - Users may experience delays receiving email messages from external domains in Exchange Online • Users may experience a delay in receiving email messages from external domains in Exchange Online. • Users may experience intermittent “Server busy” errors, affecting multiple mailboxes. We will keep you updated.

7. monitoring Sep 04, 2026, 01:11 PM UTC

   Due to initial mitigation measures implemented by Microsoft, the amount of temporary rejects has dropped significantly. For all services and in all data centres the queues are decreasing. We keep monitoring the traffic and keep you updated.

8. monitoring Sep 04, 2026, 01:11 PM UTC

   The amount of temporary rejects has dropped significantly. For all services and in all data centres the queues are decreasing. We keep monitoring the traffic and keep you updated.

9. monitoring Sep 04, 2026, 02:09 PM UTC

   Most services have been restored and are operating normally. For Email Security outbound there is still a small amount of queued to specific recipients. The error code S77714 previously returned from Microsoft changed to AS780082 and affects certain recipients. Unfortunately, new emails to these recipients are affected as well. We will continue to monitor the traffic closely and keep you updated.

10. monitoring Sep 04, 2026, 02:09 PM UTC

    Most service has been restored and are operating normally. For Email Security outbound there is still a small amount of queued to specific recipients. The error code S77714 previously returned from Microsoft changed to AS780082 and affects certain recipients. Unfortunately, new emails to these recipients are affected as well. We will continue to monitor the traffic closely and keep you updated.

11. resolved Sep 04, 2026, 03:15 PM UTC

    Microsoft has resolved the incident on their side, by disabling different machine level throttling rules. As a result we were able to sent all remaining queued message. There are no more queued messages within our infrastructure and all incoming messages are processed normally. Therefore, we close this incident as resolved.