📬Mail Server Settings
Various information about configuring Squirrel for well known mail providers
Gmail / Google Mail: POP3 / IMAP
Enable POP3 and/or IMAP in your Gmail settings: See https://support.google.com/a/answer/105694?hl=en
Create an Google App Password for Squirrel: See https://support.google.com/accounts/answer/185833
Use the App Password instead of the normal Gmail user password in your Squirrel subscription document
POP3S
pop.gmail.com
995
IMAPS
imap.gmail.com
993
Microsoft 365 Outlook Mail: POP3 / IMAP with OAuth 2.0
The support for OAuth 2.0 Client Credentials grant type with IMAP and POP3 access on the Azure platform is available as of July 1st, 2022. Please follow the steps carefully in setting up the application id and the client credentials:
Important Notes
Add the Application Type API permission Office 365 Exchange Online > IMAP.AccessAsApp or POP.AccessAsApp depending on the protocol to be used.
These API permissions do require admin consent.
Do not forget to issue the required PowerShell commands (see below).
Use the hostname outlook.office365.com in the connection document.

PowerShell Command Example
Install-Module -Name ExchangeOnlineManagement
Import-module ExchangeOnlineManagement
Connect-ExchangeOnline -Organization {Azure-Tenant-ID}
New-ServicePrincipal -AppId {Enterprise-Application-ID} -ServiceId {Enterprise-Object-ID}
Add-MailboxPermission -Identity "{Email-Address}" -User {Enterprise-Application-ID} -AccessRights FullAccess
The client secret generatzed by Microsoft 365 will expire after the specified period and will have to be renewed.
Field Assignments
Authorization Token Endpoint
https://login.microsoftonline.com/11111111-2222-3333-4444-55555555555/oauth2/v2.0/token
Authorization Scope
https://outlook.office365.com/.default
Client/Application ID
66666666-7777-888-9999-11111111111
Client Value/Secret
puG8Qak340dhfnskfrieuhnfe3dr.456saa.O
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