Otherwise, ask your O365 org admin for help.įurther details: gave a terrific answer, but if for any reason those steps aren't possible (as was my situation), the following solved the OP problem for me. Important: You need admin rights in your Office 365 organization to do that.

Enable Authenticated SMTP and click Save changes.Īfter that you should be able to authenticate using the respective account.

In the Email apps section click Manage email apps.

Select the user you are going to send emails from, and go to the Mail tab.Go to the Microsoft 365 admin center ( ) > Users > Active users.To make it simple, to enable SMTP AUTH for a single account: SMTP AUTH can be enabled in Microsoft 365 admin center or using Exchange Online Powershell. If security defaults are enabled in the organization, then SMTP AUTH is disabled. Because SMTP AUTH only uses basic authentication, Microsoft recommends to disable it on the organization level and enable it only for individual accounts that still require it. SMTP AUTH can be enabled/disabled on the organization level, or per-mailbox. Runs on: WinXP, WinVista, WinVista 圆4, Win7 x32, Win7 圆4, Win2000, WinOther, Other, Mac OS X, Mac Other, Windows2000, Windows2003, WinServer, Windows Vista, WinMobile, Windows CE, Pocket PC, Android, BlackBerry, iPhone, iPod, iTouch, Palm, Palm OS 6.0, Not Applicable, Win98, WinME, WinNT 3.x, WinNT 4.x, Win95, Unix, Linux, Handheld, Mobile Other, Java, Win 3.1x, Windows Tablet PC Edition 2005, Windows Media Center Edition 2005, Windows Mobile 2003, Windows Mobile 2005, Linux Console, Linux Gnome, Linux GPL, Linux Open Source, MS-DOS, AS, 400, OS, 2, OS, 2 Warp, OS, 2 Warp 4, Mac PPC, Mac OS X 10.5, Mac OS X 10.4, Mac OS X 10.3, Mac OS X 10.2, Mac OS X 10.1, Mac OS 9, MAC 68k, Palm OS 5.0, Palm OS 4.0, Palm OS 3.2, Palm OS 3.1, Palm OS 3.0, Palm OS 2.1, Palm OS 2.0, Palm OS 1.0, RIM, Symbian, OpenVMS, Netware, BEOS, Mac OS X 10.6, Mac OS X 10.7, Mac OS X 10.Most likely, the authenticated SMTP (SMTP AUTH protocol) is disabled in your Exchange Online organization.

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