If your Microsoft 365 mailbox was connected to Kolleno before Monday 3 August 2026, it needs to be reconnected once. It takes under a minute and you only have to do it a single time per mailbox.

Mailboxes connected on or after 3 August 2026 are already on the new connection and need nothing.

Kolleno used to reach Microsoft 365 through an older Microsoft interface called Exchange Web Services, or EWS. Microsoft is switching EWS off for Exchange Online on 1 October 2026. After that date, anything still using it stops working, and this is a Microsoft deadline rather than a Kolleno one.

Kolleno now uses Microsoft Graph, which is Microsoft's current and supported interface. New connections use it automatically. Existing connections were left alone deliberately so nothing broke overnight, which is why they need this one manual step.

Reconnecting moves your mailbox onto Graph. Nothing about how you use Kolleno changes.

Go to Settings, then Email profiles, and open the profile for the mailbox.

Sign in with the same Microsoft account the mailbox used before. The mailbox that gets connected is whichever account you sign in with, so signing in with a different account will connect the wrong mailbox. If your browser remembers another Microsoft account, check the account name on the Microsoft screen before continuing.

We highly recommend doing this operation in a private browser window, to avoid your personal account getting connected by mistake (sometimes Microsoft connects you automatically without prompt).

Do the disconnect and the reconnect in one sitting. While the mailbox is disconnected, Kolleno cannot pick up replies sent to that address.

The confirmation message when you disconnect warns that emails to the address will no longer be detected, and it lists any workflows that use the profile. That is the standard disconnect warning and it is expected here. Nothing is deleted, and the workflows are not removed.

Kept as it is:

Once you have signed back in, the profile works exactly as before.

Some mailboxes have no one who can sign in, typically a shared inbox like ar@yourcompany.com where sign-in is blocked by design. Those cannot use the personal sign-in above and need your IT admin to connect them instead, which also puts them on Graph.

See Personal mailbox or RBAC application access: choosing how to connect Microsoft 365 for which route applies, and forward For IT admins: giving Kolleno access to one shared mailbox (Microsoft 365) to whoever administers your Microsoft 365 tenant.

There is no benefit to waiting, and a mailbox that is still on the old connection on 1 October 2026 will stop sending and receiving. If you have several mailboxes to move, or you are not sure which of yours are affected, get in touch and we will check for you.