Office 365 SMTP authentication failing, even with correct account information

Anonymous
2020-02-10T16:38:43+00:00

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.

Microsoft 365 and Office | Subscription, account, billing | For home | Windows

Locked Question. This question was migrated from the Microsoft Support Community. You can vote on whether it's helpful, but you can't add comments or replies or follow the question.

0 comments

48 answers

Sort by: Oldest
Most helpful Newest Oldest
  1. Anonymous
    2021-02-28T13:30:55+00:00

    Yes - I guess it is Microsoft's way of inducing developers to use OAuth2 instead of basic authentication! And since the latter has been deprecated for IMAP and POP for a couple of years (but was only recently 'undeprecated' again - at least temporarily) it seems fair enough I guess, although it has given lots of people, me included, a headache trying to get things working. SMTP AUTH with basic authentication was never officially deprecated but branded as 'insecure'. It's worth noting, however that Conditional Access policies are not available 'from the AAD menu' in Business Basic or Business Standard accounts, although low-level policies such as 'switch on modern authentication' or 'block basic authentication' can be defined and then be allocated to an account (rather than broad-brush tenant-wide) using 365 Powershell.

    Was this answer helpful?

    0 comments
  2. Anonymous
    2021-02-28T18:45:12+00:00

    Followed instructions provided and disabled modern authentication. via MS 365 Admin center Confirmed this changed Azure as well. Contact Us email from my business website were received. Back in business, for now. Thanks all for the help.

    Was this answer helpful?

    0 comments
  3. Anonymous
    2021-04-02T09:48:38+00:00

    Hello @ll,

    I had the same problem with a none premium version (no access to MFA configuration).

    A very good structured answer without any needs of Powershell etc. is found here:

    https://metablogue.com/send-wordpress-emails-with-microsoft-365/

    It tells you exactly how your issue with WP Mail SMTP Plugin can be solved step by step.

    Best wishes

    inkognitus

    PS:

    When you changed your configuration, please wait about 15 - 30 minutes before you test it. Obviously it needs some time to synchronize...

    Was this answer helpful?

    2 people found this answer helpful.
    0 comments
  4. Anonymous
    2021-04-08T22:08:20+00:00

    Hey everyone,

    For anyone facing the failing authentication issue, I can suggest one thing to try that did solve the problem for me. Granted, there are many possible sources of the problem, so this suggestion won't necessarily fix the issue of course.

    In your Microsoft 365 Admin Center under the User tab, you have the ability to allow/disallow Email Apps. Head over to https://admin.microsoft.com/AdminPortal/Home#/users and click on the user that is facing the issues. In the "Email" tab of the modal that opened you'll be able to manage the Email Apps. Select Authenticated SMTP and click save.

    In our specific case that fixed the issue.
    I hope that helped :)

    Cheers

    This saved the day for me! Excellent. Can’t thank you enough.

    Was this answer helpful?

    9 people found this answer helpful.
    0 comments
  5. Anonymous
    2021-05-18T13:05:38+00:00

    May be a help to other readers: I had a similar issue, with the same log messages. When I tried to use the password to login to my outlook account, it required me to change the password first. After it, it  works. So it seems that when a password is expired, this message appears as well.

    Was this answer helpful?

    0 comments