Office 365 and No-Reply/unmonitored email addresses management and usage

A noreply email address comes in handy for many case studies, mainly for transactional purposes, being sent within a website, an App, or any automated flows.
Creating a simple noreply@ email account it's a no-brainer, but when required in creative marketing strategies, won’t be enough.

Let's take a look at this scenario

AppName | SendFrom            | Info                             |
--------+---------------------+----------------------------------+
Website | news@7bis.eu.org    | News for site members            |
Website | hi@7bis.eu.org      | Welcome emails, password reset   |
CRM     | hi@7bis.eu.org      | Onboarding emails, password reset|
CRM     | invoices@7bis.eu.org| Everything abouts invoices       |

Our Website want's to send emails using two noreply/unmonitored email accounts, our CRM App wants the same, while one of our noreply@ email address (hi@7bis.eu.org) need to be used on both Apps. Does it look like a Many-to-Many relationship? Yes, because it is, and this is the approach we will focus on from now on.

Of course, we can do it the easy way, create three Office 365 accounts, send authentication details for both development teams (Website and CRM), and keep a note that if we ever need to reset the "hi@7bis.eu.org" account password we shall announce both development teams about that. Ah, and you will have to deal with the "unmonitored" status of the "hi@7bis.eu.org" Office 365 account/email address. Then you can stop here, no need for more reading.

Sending Office 365 emails using noreply/unmonitored email addresses - the "relationship way"

AppName | LoginWith                 | SendAs              |
--------+---------------------------+---------------------+
Website | WebsiteMaster@7bis.eu.org | hi@7bis.eu.org      |
CRM     | CrmMaster@7bis.eu.org     | hi@7bis.eu.org      |

Both Website and CRM Dev Teams will be able to send emails as (SendAs) "hi@7bis.eu.org", while both teams authenticate (LoginWith) using individual credentials. It's a One-to-Many relationship here, one noreply email address (hi@7bis.eu.org) to many teams (Website, CRM), or, if you prefer, an Office 365 Group with many allowed senders.

"Unmonitored email address" doesn't necessarily mean "no one check emails that come to that email address". It's (and that's the way it should, at the logic level at least) "This email address won't receive any emails".

We will create one Office 365 group (Distribution list), using "hi@7bis.eu.org" as the associated email address, without members (this way, the email address won't receive/distribute any incoming emails), with closed members join, hidden from GAL.
Further, we can add management (Send As) Office 365 accounts (eg WebsiteMaster@7bis.eu.org and CrmMaster@7bis.eu.org) to it. Many-to-One.

Create a new Distribution list group

Remember, no members allowed, no display in GAL

After a while (sometime instantly, sometimes after a few seconds, maybe a minute), the new group will appear, ready to be managed (click on the group name).
1.1 - Settings->[x]Hide this group from the global address list->Save
1.2 - Settings->Edit manage delegates->[search for, add it and set "Send As" permission for whatever Office 365 account needed, eg WebsiteMaster@7bis.eu.org and CrmMaster@7bis.eu.org in our case].

Account not found/not yet created? Go ahead and create one (in Microsoft 365 admin center - MAC). If found, check the SMTP settings of this account

Create an Office 365 account, set SMTP access

Note that to benefit from the SMTP protocol (that's it, no-reply/transactional emails are usually sent by Apps using the SMTP protocol), these accounts (eg WebsiteMaster@7bis.eu.org and CrmMaster@7bis.eu.org in our case) needs to be licensed with an Exchange Online Plan / Exchange Online Kiosk (have a mailbox attached and SMTP enabled)

[x]Authenticated SMTP, uncheck/check other apps as per need

Now, you can go back to EAC -> hi@7bis.eu.org group and add (as Send As delegate) the newly created/SMTP enabled WebsiteMaster@7bis.eu.org account.

That's all, now you can create as many No-Reply distribution groups and delegate (for each group) who can send emails using the No-Reply group email address.

Let's take a test drive too, we will authenticate using the WebsiteMaster@7bis.eu.org account and send emails using hi@7bis.eu.org.
The test was conducted using the PowerShell Send-MailMessage cmdlet (any programming language that speaks SMTP will work) and the result is ...

The correspondent received the email from "hi@7bis.eu.org"