Hi @User10 ,
Letters come to the device with Android immediately. 1-3 minutes. To Outlook 365 (Win 10) - in 1-5 hours.
Sounds like the delay-receiving issue might indeed be related to your Outlook client. When the issue occurs, have you tried manually clicking the "Send/Receive All folders" like below to see if the issue has any difference?
If manually send/receive can indeed work, changing send/receive group settings and modifying the "Schedule an automatic send/receive every n minutes" option to a shorter time(1 minute for example) might be able to make your delay-receiving issue better. For more information: Change send/receive group settings.
If this not your issue, please try to provide me with more specific information related to your issue.
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