Username length issue with SMTP in Azure Communication Services

Jonny Sharp 75

Hi,

I'm testing "Email SMTP as a Service" that is in preview within "Azure Communication Services". I was so excited to hear about it because we've just done an Exchange migration to O365, and this feature will help mop up the remaining SMTP client apps without having to deploy any SMTP relay infrastructure.
It was very easy to set up and get working for 2 test domains.... BUT...

The instructions state that a Service Principal must be used as the user. And with this, the username must be in the following format:
<Azure Communication Services Resource name>|<Entra Application ID>|<Entra Tenant ID>

This makes for a super long username. Mine was 94 characters! It worked in one SMTP client software but others I've tested have character length limits such as 60 characters.

The 2 pipes (or dots), App ID and Tenant ID guids mean that the username has 74 characters before the ACS resource name prefix is added!

I thought it might work with a UPN as username, so I added a user to the IAM Role Assignment, but that didn't work, returning error code "535 5.7.3 Authentication unsuccessful".

Is there a workaround? Because without one, the use of this SMTP feature will be severely limited.

Thanks,

Jonny S

brtrach-MSFT 16,926 Reputation points Microsoft Employee

2023-12-11T03:40:35.8966667+00:00

@Jonny Sharp Hi, thank you for reaching out. As you mentioned, this feature is in preview state currently. This means that we do not recommend the feature for production use as features are still being matured out into their GA state and there might be known bugs.

With that being said, let me reach out to the team and see if this is something they are aware of. I hope to reply back by mid-week.
brtrach-MSFT 16,926 Reputation points Microsoft Employee

2023-12-15T03:06:23.6033333+00:00

@Jonny Sharp I have not forgotten about your ask. I am still in discussion with the product group. Please give me a little more time. Thanks
Dag Efjestad 0 Reputation points

2024-02-01T13:44:26.39+00:00

Did you do anything with this?
Matt Mauchley 5 Reputation points

2024-02-06T22:53:43.77+00:00

We want information on this as well. Want to move our SMTP apps to Azure but most only support 50 character limit so it won't work as currently architected.
Ashley - Tetrabyte 20 Reputation points

2024-04-29T22:22:24.42+00:00

Just wanted to raise that I think i'm facing similar issues using CMailGUI 0.04 as a test platform
Veselý, Ondřej 0 Reputation points

2024-05-28T12:08:35.93+00:00

I have exactly the same issue in UniFlow, Canon printers and in Navision(basically all my SMTP use cases).

I would assume that the length of the username AND password is going to be a major issue pretty much in majority of the applications where this could be used.
Mischa Rohleder 0 Reputation points

2024-05-29T13:36:28.4033333+00:00

I am having the same problem.. Is there any update?

We are cut at 64 characters
Thomas Oeser 0 Reputation points

2024-07-23T15:51:05.92+00:00

@brtrach-MSFT , any news regarding the character length issue for the username? We have some large enterprise customers willing to test the Azure Communication services relay functionality but this is a blocker for them. Especially printers have a character length limit of 64 characters for username field but as others already mentioned other applications have similar restrictions. This needs to be addressed to make this product usable.
Lorenzo Cernecca 6 Reputation points

2024-08-05T06:32:12.1566667+00:00

I have similar needs looking to use ACS as a SMTP solution for devices that don't support modern authentication. An example is a Dell iDRAC which appears to have a 50 character username limit.

If I only include the <Entra Application ID>|<Entra Tenant ID> component of the ACS username I am seeing 75 characters which makes it useless for this purpose. As I created a descriptive <Azure Communication Services Resource name> the combined total of my username came to 111 humorous characters.
Joe Widi 25 Reputation points

2024-09-05T20:36:03.94+00:00

I have this same issue; the username is entirely too long for even a brand-new app we're installing. We are actually stuck at a 50-character limit.
Brian House 0 Reputation points

2024-10-04T19:00:08.95+00:00

@brtrach-MSFT Did this user ever give you details to pursue this with the product group? I just ran into this exact issue today and will gladly relay my experience
Frank E 0 Reputation points

2024-10-07T18:14:32.9533333+00:00

@brtrach-MSFT I have the same issue. Can you please give us an update?
Frank E 0 Reputation points

2024-10-08T08:54:07.1833333+00:00

Is there any update on this? It's really annoying. Now i have to use a third party service.
Patrick Helm 5 Reputation points

2024-10-17T05:44:45.9466667+00:00

I'm facing a Kyocera vendor SMTP 64 character limit for username as well. :( All the effort to get the things working, to find this the blocker.
Alex Pettigrew 5 Reputation points

2024-11-04T22:50:08.59+00:00

If it eeks anyone below the limit their are facing in their application, you are able to remove the dashes in the app/tenant ID. But I am also looking for this to be fixed to be able to reliably use this product. Most legacy apps requiring smtp auth were simply not built with expectations of usernames this long.
Nebhuth, Garry 0 Reputation points

2024-11-20T15:39:56.49+00:00

next try..any updates ?
Link Martin 0 Reputation points

2024-12-11T14:14:10.6233333+00:00

@brtrach-MSFT Hi, is there any chance that the short usernames will come soon. We want to switch our MFP to this services, but we can´t because the usernames are to long.

1 answer

brtrach-MSFT 16,926 Reputation points Microsoft Employee

2023-12-16T05:07:22.95+00:00

@Jonny Sharp Good news! The product group wants me to gather some information from you so they can look into whether or not it would be possible to address this limitation.

Can you please send me an email to azcommunity@microsoft.com with the subject as ATTN: Bryan. I will then reply with the information we need for the product group to begin their consideration.
Please sign in to rate this answer.

1 person found this answer helpful.
Peter Paul Bartolo 0 Reputation points

2024-01-03T08:55:07.26+00:00

Was there any uptake/progress on this?

Jonny Sharp 75 Reputation points

2024-01-04T15:14:13.5766667+00:00

Hi @brtrach-MSFT . Sorry for not responding sooner, I didn't get a notification about your messages. I've just send the email to you as requested.
Kind regards,
Jonny

Jonny Sharp 75 Reputation points

2024-01-04T15:24:22.01+00:00

Hi @brtrach-MSFT - further to my message above, my email to azcommunity@microsoft.com is being rejected.

brtrach-MSFT 16,926 Reputation points Microsoft Employee

2024-01-09T17:07:15.44+00:00

@Jonny Sharp My apologies but I was out of the office for the holidays and just came back today.

Mia reached out to me and let me know you found a way to make contact via support case.

The product group is hoping to address this matter in a future update. Mia will work with you on gathering your use case scenario to ensure the product group can address your issue in the coming months.

Let me know if I can be of further assistance.

Logan Cook 5 Reputation points

2024-01-25T21:16:31.8966667+00:00

We're actively looking for a solution to this as well. Other than this limitation, the preview has been working beautifully.

Nyberg Mika 0 Reputation points

2024-06-26T12:11:29.96+00:00

Is there a solution for this? I am facing the same issue with Microsoft Dynamics365 FO smtp settings, 64 being maximum length for username

Joe Widi 25 Reputation points

2024-09-05T20:43:00.6433333+00:00

@brtrach-MSFT Any updates on this particular issue?

Logan Cook 5 Reputation points

2024-10-04T17:56:50.4866667+00:00

Entra application IDs are unique as-is. Including the tenant ID in the username is entirely redundant. It'd also be possible to have it accept either the version with or without tenant ID. There's no good reason for this still being an issue after almost a year.

Frank E 0 Reputation points

2024-10-08T08:53:12.32+00:00

@brtrach-MSFT Is there any update on this?

Molenbuur, Imko 0 Reputation points

2024-12-16T21:49:59.91+00:00

@brtrach-MSFT can you please give an update on this issue, we're facing the same issue for one of our customers on a SAP S/4HANA 2023 system.

Emmitt Houston 0 Reputation points

2024-12-25T05:51:18.7433333+00:00

I'm setting this up as well on an HP MFP M283fdw (table top MFD) that does not support OAuth2.0. The username and password fields are limited so the password field won't fit the client secret and the username fit but, will likely be silently truncated. This is also going to be an issue on a Konica Minolta Bizhub C258i also using scan to email smtp with no OAuth2.0 support.

Should I follow the same guidance from 2023 and email azcommunity@microsoft.com with the subject as ATTN: Bryan?
Sign in to comment

Use comments to ask for clarification, additional information, or improvements to the question.

Share via

Username length issue with SMTP in Azure Communication Services

1 answer

Your answer