2018.03.23 12:15 Due to congestion on outgoing mail we were able to detect a pattern in delivery delays – business hosting on outlook.com / office365.com seems to be affected.
You may see mail delays, but the issue relates to their reception –not our sending.
Errors generated by the Microsoft servers include:
451 4.4.3 Temporary server error. Please try again later ATTR2 [TO1CAN01FT007.eop-CAN01.prod.protection.outlook.com]
421 4.3.2 The maximum number of concurrent server connections has exceeded a limit, closing transmission channel (TO1CAN01FT005....
Summary: The mail system is designed to fail safe. Mail messages destined for users on outlook.com etc. are currently stuck in queues and may be returning delivery warnings. They should eventually go through - if they do not, you will receive a delivery failure notice. Please contact support with any questions.
Updates will be posted as available.
This may also affect voicemail to email - if you are hosted with Microsoft, please monitor for missed calls as you may receive voicemail by email delayed.
We are launching a new service soon with delivery notification to TXT message - ask us if you have any questions?
2018.03.23 15:30 Mail queues are clearing - the issue seems to be resolved. Thank you!