Office 365 SMTP authentication failing, even with correct account information

Anonymous

On my Wordpress site I've run into a problem in the last day or so, where emails simply fail to send. Before today it was running flawlessly for two months. The account information/password/username etc have not changed in that two months.

I'm using a Wordpress plugin called WP Mail SMTP to facilitate the sending of all outgoing emails. The error log I'm getting from the email test on that is as follows:

Versions:

WordPress: 5.3.2

WordPress MS: No

PHP: 7.3.14-5+0~20200202.52+debian9~1.gbpa71879

WP Mail SMTP: 1.8.1

Params:

Mailer: smtp

Constants: No

ErrorInfo: SMTP Error: Could not authenticate.

Host: smtp.office365.com

Port: 587

SMTPSecure: tls

SMTPAutoTLS: bool(true)

SMTPAuth: bool(true)

Server:

OpenSSL: OpenSSL 1.1.1d 10 Sep 2019

SMTP Debug:

2020-02-10 16:36:56 Connection: opening to smtp.office365.com:587, timeout=300, options=array ()

2020-02-10 16:36:56 Connection: opened

2020-02-10 16:36:56 SERVER -> CLIENT: 220 LNXP123CA0008.outlook.office365.com Microsoft ESMTP MAIL Service ready at Mon, 10 Feb 2020 16:36:55 +0000

2020-02-10 16:36:56 CLIENT -> SERVER: EHLO www.*****.com

2020-02-10 16:36:56 SERVER -> CLIENT: 250-LNXP123CA0008.outlook.office365.com Hello [***]250-SIZE 157286400250-PIPELINING250-DSN250-ENHANCEDSTATUSCODES250-STARTTLS250-8BITMIME250-BINARYMIME250-CHUNKING250 SMTPUTF8

2020-02-10 16:36:56 CLIENT -> SERVER: STARTTLS

2020-02-10 16:36:56 SERVER -> CLIENT: 220 2.0.0 SMTP server ready

2020-02-10 16:36:56 CLIENT -> SERVER: EHLO www.zestpromotional.com

2020-02-10 16:36:56 SERVER -> CLIENT: 250-LNXP123CA0008.outlook.office365.com Hello [***]250-SIZE 157286400250-PIPELINING250-DSN250-ENHANCEDSTATUSCODES250-AUTH LOGIN XOAUTH2250-8BITMIME250-BINARYMIME250-CHUNKING250 SMTPUTF8

2020-02-10 16:36:56 CLIENT -> SERVER: AUTH LOGIN

2020-02-10 16:36:56 SERVER -> CLIENT: 334 VXNlcm5hbWU6

2020-02-10 16:36:56 CLIENT -> SERVER: c2FsZXNAemVzdHByb21vdGlvbmFsLmNvbQ==

2020-02-10 16:36:56 SERVER -> CLIENT: 334 UGFzc3dvcmQ6

2020-02-10 16:36:56 CLIENT -> SERVER: QmFkMzM4MzA=

2020-02-10 16:37:02 SERVER -> CLIENT: 535 5.7.3 Authentication unsuccessful [LNXP123CA0008.GBRP123.PROD.OUTLOOK.COM]

2020-02-10 16:37:02 SMTP ERROR: Password command failed: 535 5.7.3 Authentication unsuccessful [LNXP123CA0008.GBRP123.PROD.OUTLOOK.COM]

SMTP Error: Could not authenticate.

2020-02-10 16:37:02 CLIENT -> SERVER: QUIT

2020-02-10 16:37:02 SERVER -> CLIENT: 221 2.0.0 Service closing transmission channel

2020-02-10 16:37:02 Connection: closed

SMTP Error: Could not authenticate.

Does anyone have any ideas at all? I'm completely at a loss here.

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48 answers

Anonymous

2020-12-03T14:35:26+00:00

Thanks Timme B81. To run the Powershell code I had to use an admin Powershell, and in it first run Set-ExecutionPolicy RemoteSigned

https://answers.microsoft.com/en-us/msoffice/forum/msoffice_outlook/error-when-importing-pssession-on-o365/3eaf0b1a-b5e0-467d-a113-06146a17a9c6

In my case SmtpClientAuthenticationDisabled was already false, so I'm still stuck. There is a good list of various settings to check at https://kontext.tech/column/aspnet-core/481/send-emails-using-microsoft-365-in-aspnet-core, but they're all ok too.
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Anonymous

2020-11-14T12:04:18+00:00

ok, thanks!
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Anonymous

2020-11-14T10:35:03+00:00

MSFT's July update Basic Authentication and Exchange Online is well worth reading, in particular about the overlap between two groups of settings: the tenant's Security Defaults and Exchange's Authentication Policies and when each should be used to selectively block Basic Authentication.
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Anonymous

2020-11-14T08:40:19+00:00

Everything was checked but had to go open the window and then click save changes without changing anything and now SMTP works.
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Anonymous

2020-10-24T17:45:41+00:00

@all i think this ist the solution:

I had the same Problems, old offic365 accounts work, new accounts did not work. After searching for 5 hours i get a solution:

In the old accounts SmtpClientAuthenticationDisabled is false by default on online Exchange, in the new accounts it is True by default.

I had to set it to false by exchange online powershell and also hat do go to e-mail-apps and set the hook to authenticated smtp

after that it worked. Here you can read what is to do by exchange powershell:

https://docs.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/authenticated-client-smtp-submission

Steps in Powershell:

$UserCredential = Get-Credential

$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection

Import-PSSession $Session -DisableNameChecking

Take a look if it is True: Get-TransportConfig (if there is True set to false)

Set-TransportConfig -SmtpClientAuthenticationDisabled $false

Take a look again if it works: Get-TransportConfig

Remove-PSSession $Session

In Admin Center --> acitve Users --> click the user --> email-apps --> click the hook --> authenticated smtp

With this combination it worked for me. Hope this can help you all

This was exactly what I was looking for, it was hard to find. I would like to add that in my case, I had to not only do this but also do it at the user account explicitly because it had already been created with the previous global defaults. Thanks a lot.
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