From 6ba2f1f3e2d7e6f2f37fb5b0b5d008873beb77f9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Burak=20Kaan=20K=C3=B6se?= <bkaankose@outlook.com>
Date: Mon, 29 Dec 2025 14:46:31 +0100
Subject: [PATCH] Make sure outlook correctly calls datetime for delta api.

---
 Wino.Core/Synchronizers/OutlookSynchronizer.cs | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Wino.Core/Synchronizers/OutlookSynchronizer.cs b/Wino.Core/Synchronizers/OutlookSynchronizer.cs
index 19ea1421..42ba1f75 100644
--- a/Wino.Core/Synchronizers/OutlookSynchronizer.cs
+++ b/Wino.Core/Synchronizers/OutlookSynchronizer.cs
@@ -1631,8 +1631,9 @@ public class OutlookSynchronizer : WinoSynchronizer<RequestInformation, Message,
             {
                 _logger.Information("No calendar sync identifier for calendar {Name}. Performing initial sync.", calendar.Name);
 
-                var startDate = DateTimeOffset.UtcNow.AddYears(-2).ToString("o");
-                var endDate = DateTimeOffset.UtcNow.ToString("o");
+                // ISO 8601 format as expected by Microsoft Graph API (e.g., "2019-11-08T19:00:00-08:00")
+                var startDate = DateTimeOffset.UtcNow.AddYears(-2).ToString("yyyy-MM-ddTHH:mm:sszzz");
+                var endDate = DateTimeOffset.UtcNow.ToString("yyyy-MM-ddTHH:mm:sszzz");
 
                 eventsDeltaResponse = await _graphClient.Me.Calendars[calendar.RemoteCalendarId].CalendarView.Delta.GetAsDeltaGetResponseAsync((requestConfiguration) =>
                 {