"5.7.139 Authentication unsuccessful, account locked." from Outlook SMTP gateway

Eugene K 5

I use gmail to send my @hotmail.com emails through smtp-mail.outlook.com.

Periodically, I am getting

"5.7.139 Authentication unsuccessful, account locked. Contact your administrator."

response from outlook.com's SMTP gateways forwarded to me by Gmail.

This does not happen for every email. Only sometimes.

Plus, I can log in into outlook.live.com and see my email with no problem.

So, my account is not fully locked.

Requesting help on how to fix this.

Another possibly related issue is that a couple of times I tried to ReplyAll to an email thread with about 50 recipients and got NDR receipts on all the recipients. I read somewhere that nowadays Outlook imposes a 100 recipient/day limit on the use of SMTP gateway but I don't think I ever went over it.

Thank you in advance -- Eugene

2 answers

SokiGuo-MSFT 24,126 Reputation points Microsoft Vendor

2024-04-02T07:54:27.49+00:00

Hi @Eugene K

Does the problem happen on the Outlook client?

How did you configure the account?

According to the error message, there may be other two possible causes of this issue. Please refer to this link and check point 3 (Azure Security Defaults) and point 4 (Conditional Access policy): Error: Authentication unsuccessful.

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Eugene K 5 Reputation points

2024-04-02T19:52:17.65+00:00

Hi SokiGuo, thank you for your help.

RE: Configuration: On the Gmail side I have the following settings for my @Hotmail account:

"<...@hotmail.com>

Mail is sent through: smtp-mail.outlook.com

Secured connection on port 587 using TLS"

Is this correct? It works in all cases except sometimes. TLS is a secure protocol so I am not sure why I need to lower security settings for my account. Also, as an Outlook user I manage my account through account.live.com, not through Azure Portal.

RE: "Does the problem happen on the Outlook client?":

It did not in a few cases I had to use to Outlook web client. But I don't have good statistics on this.

Eugene K 5 Reputation points

2024-04-02T19:54:17.08+00:00

Ignore. The bad interface of learn.microsoft.com made me to double post my comment.

SokiGuo-MSFT 24,126 Reputation points Microsoft Vendor

2024-04-03T05:52:30.99+00:00

Hi

Looks like the issue is more related to your account, please kindly understand that the Outlook tag here we mainly focus on general issues about Outlook desktop client. It's recommended to contact the mailbox admin and account support directly to get more help.

Eugene K 5 Reputation points

2024-04-03T18:53:02.9166667+00:00

Thank you SokiGuo! Can you advise on the best way to contact the mailbox admin and account support?
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Phil S 0 Reputation points

2024-04-22T20:19:19.92+00:00

I too am having this sporadically over the last few weeks. Microsoft support was useless. It seems to last between a few minutes and a few hours each time. I definitely don't send a lot of mail through SMTP:

334 VXNlcm5hbWU6 UGFzc3dvcmQ6 5.7.139 Authentication unsuccessful, account locked. Contact your administrator. [MW4PR04CA0155.namprd04.prod.outlook.com 2024-04-22T20:13:34.321Z 08DC620A8066B221]
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Eugene K 5 Reputation points

2024-04-22T20:56:36.42+00:00

I haven't seen this happen to me since I deleted and recreated Hotmail/Outlook account in Gmail under "Send mail as".

Phil S 0 Reputation points

2024-04-22T21:01:01.48+00:00

I've tried that. When it fails, it stays broken for a random amount of time, and when I try to re-add, it gives the same "Authentication unsuccessful, account locked" message until M$ fixes whatever is causing this frustration.

Maxime Gagnon 11 Reputation points

2024-05-13T03:13:40.5+00:00

Thank god I am not the only one with the issue...
Me and some other persons are using a invoicing software and we send invoices copy via email to our customers using SMTP (and in this case smtp.office365.com or smtp-mail.outlook.com)

For the last few weeks, we have the same issues . Either it says "Authentication unsuccessful, credentials are invalid." or "Authentication unsuccessful, account locked". It both case, credentials are valid and the account is NOT locked. We can log on outlook.com or use our email via Outlook app without any problem.

Sometime it works fine for a couple of hours until the issue comes back.

Sadly, Microsoft support did not help much and instead gaslighted us by saying no other reports have been made concerning such an issue and they are blaming our software provider (which is not to blame as no change has been made in the last few months and all other email providers (Gmail, Yahoo, self-hosted smtp/email provider just to name a few) do not have these issues...

I don't know if it's linked to it, but it seems there is a lot of unsuccessful attempts at logging to my email if I check the sign-in activity (from Morocco,Russia, Afgnanistan, Spain, USA, etc). I guess the smtp auth is blocked for a few hours/minutes when this happens. Otherwise I have no idea what's going on...

GIANFRANCO STEFANELLI 0 Reputation points

2024-05-20T10:41:52.3066667+00:00

News for this problem??

Maxime Gagnon 11 Reputation points

2024-05-21T18:30:18.5466667+00:00

We did fix our issue.
This issue is still present if using basic smtp auth, being very intermittent.

But our software provider released an update last week to use OAuth 2 and since then, it seems to be ok.

But as they (our software provider) told us, although it is working, this shouldn't be the real solution (except for Exchange online and MS365 emails of course).

If Microsoft indicates in the documentation that using email/password for SMTP Auth is still available for personal email account using Hotmail/Live/Outlook, it should be working with basic SMTP Auth at all time.

I didn't test it using smtp auth in the last few days so who knows, maybe it's fixed now?

Eugene K 5 Reputation points

2024-05-22T21:31:47.2833333+00:00

I (the original poster) still periodically see this issue even after I reentered all the credentials in Gmail under "Send mail as" as a new account.

Even worse. I suspect Hotmail/Outlook.com footballs some of incoming emails as I don't receive emails from some of my subscriptions or when buying online, but only some. I can't reliably reproduce it. Will update here once I have clarity.

Possibly, it is time to move away from everything Microsoft, however sad and painful it would be.
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"5.7.139 Authentication unsuccessful, account locked." from Outlook SMTP gateway

2 answers