SMTP issues with Office365

Hi guys,

I am having some issues with SMTP setup in Auth0 where external users are not receiving our emails. I have set up SPF (basic) and DKIM activated, I have whitelisted all IPs stated in the Email Provider page, when I analyze the email header sent on mxtoolbox (result at: I get failed on “SPF Failed for IP -” (this IP changes, and are amongst the listed ones from the Email Provider page, which I already whitelisted in Office365 admin pages).
Also, it seems like, although the DKIM is active, the signature is not added when emails are sent using Auth0.

I’m not really sure what the underlying issue is, since it complains about SPF issue I’ll start with mentioning my SPF record, which has the value: “v=spf1 -all”

Hope you can help :slight_smile:

Edit: Just to clarify, I have SMTP set up with same credentials in my C# project, from here the emails seems to be delivered as expected to recipients.


I resolved the SPF issue, whitelisting the IP addresses mentioned in the Email Provider of Auth0 wasn’t enough, I needed to add all the IP addresses to the SPF record in my domain DNS settings.
Now I am stuck at the next step with missing DKIM signature (it is however active and has been active for a long time on my domain)

Still an issue, last week I got support from Microsoft to correctly set up DKIM signatures for both my domains, and whenever emails are sent through Auth0 (such as forgot password, welcome email etc.), the emails are not received at users end, and testing with mxtoolbox on analysis of email headers, shows DKIM signatures are missing. This only happens on emails sent from Auth0 through the SMTP.
Please help.


Response from Microsoft:

Since we have confirmed that your emails includes both SPF and DKIM headers, these are already working and it’s up to the receiving mail servers how they will will deliver emails from your domain to the recipient mailbox.

As you have checked, the message trace indicates all emails are sent. I suggest that you coordinate with the admin of the receiving mail server to check on their end what happened to email sent from your domain - since emails from your domain already include the three headers needed for email validation/authentication (SPF, DKIM and DMARC).

Bump, help please :slight_smile:

Bumpy, still awaiting response

Bump, still awaiting response

Bump, can I get some support? Case was opened 6 weeks ago and not a single response.

Hey there!

Terribly sorry for the delay in response. We’re doing our best to provide you with best developer support experience but sometimes the number of incoming questions is too big for our small team. Let me dive into your hurdle and get back to you soon!

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Can you send me your tenant name via private message? Thank you!

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I was searching through our internal knowledge base regarding issues with email but unfortunately didn’t find anything. I just opened an internal engineering ticket to have our engineers look into that.

Once I have any update from our Email Delivery engineering team, I’ll let you know!

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Hi Konrad,

Any news yet? :slight_smile:


I repinged the engineering team working on that

Hello Konrad,

Since this is still unresolved and you decided to close the private thread we had ongoing shortly after after I bumped it two days ago, can you please give an update here? Thanks.

Hey there!

Sorry it closed automatically. I just reopened it. I’m still discussing it internally as the internal ticket was hanging there and due to holiday period and low bandwidth nobody taken it so I’m still working on that.

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Seeing the same issue for our Auth0 tenants as well, so will be interested in resolution for this.

Bump, any news on this? :slight_smile:

It’s been almost a month since the last bump, and still no response.
Can you please resolve this asap? It can’t be right that something as urgent as this has not been resolved yet…

Hey guys, we are gonna be releasing our product soon and this isn’t working for us. we really need this looked into!

We have the same issues. We want to use our Outlook 365 STMP to send out emails, I have it setup and the test email sent out has worked but when users wish to login via the email code they never receive the email.