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Azure B2C Email's slowly/not making it to customer mailboxes and being wrongfully marked as spam

Tuning in


At the business I work for we have just migrated our customer auth and account services to Azure B2C however after some complaints from customers and a test with my own personal virginmedia email address I have found that Email verification code emails can take anywhere from 30 minutes to 24 hours to make it to the mailbox - and when they do they wrongfully go into spam. This obviously isn't ideal for our customer journey. I found this odd as emails are sent from Microsofts own domain rather than the companies domain - I have corresponded with a rep at Microsoft who say the issue is on Virgin's end. How do I go about getting us out of any greylists and improve deliverability and speed.

I am part of the software dev team and can provide any extra information if required.


Forum Team
Forum Team

Hi there @Michael-H


Thank you so much for your post and welcome back to the forums.


I'm so sorry to hear that you have noticed your clients facing this issue, can I ask if there are any attachments that are also sent in these emails? 


Thank you.

Hi Ashleigh,

There are no attachments its a pretty plain email from address featuring an embedded company logo and a 6-digit OTP to allow for logging into an account. I can forward or screenshot an example email if that would be helpful.

Thanks for clarifying. 

Is it purely the verification code emails that are being sent delayed and end up in spam?

Any other emails sent from the mailbox, do they arrive okay?

Forum Team

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Hi Ayisha,

Yes only these email verifications. We do not use Microsoft to facilitate any other sort of communications, they provide our Identity services so send emails from their mailbox address. Just to test if our domain despite not being used for these OTP emails had any effect I tested sending from our own Email address and emails came through instantly. It appears that Virgin have greylisted emails for Azure B2C clients where their emails come from as I mentioned in an earlier post and also have some sort of performance issue for receiving them. Fixing this would improve our customer journey.

Michael Hughes

Hi Michael-H thanks a lot for your reply.

I'm going to send a PM to take some details to see if we can get this resolved for you.

Kindly expect the PM from me to arrive shortly and respond directly when you can!
Many thanks


Hi Tom,
I have just replied to you in PMs about the situation.

Hi Tom_W1,

Did you find a solution to this? We did a similar migration to Microsoft Azure AD B2C and have many customers on virginmedia. Their OTP (i.e. a 6 digit verification code) emails from are being delayed for multiple hours. Since the OTP codes are only valid for 10 minutes this is stoping virginmedia from accessing their accounts. Any help would be appreciateed.



Hi John, just saw you also replied to my Q on the MSFT forums about this issue when we were experiencing it last year. In the end, I didn't fully follow up on the issue with Virgin when I should have - however as far as I can tell the situation slightly improved with time. I'd be happy to re-open and provide the necessary info to the tech support team to get this resolved for all of us who use B2C.


Thanks Michael - I'm also raising with Azure support directly so will feed back how I get on.