Historically, Exchange has used a user’s primary SMTP address as the From address when sending messages. Other SMTP addresses assigned to a user (e.g., proxy addresses, also known as aliases) were ma...
Updated Oct 21, 2024
Version 11.0
Blog Post
We have a strange and special case.
We have an Exchange Modern Hybrid Setup with centralized mail flow.
We have identified an issue on the automatic reply mechanism when the setting "Turn on sending from aliases" is enabled.
If enabled, then the sender e-mail address of the automatic reply is {Alias}@{Tenant}.mail.onmicrosoft.com
e.g. email address removed for privacy reasons
If disabled, then the sender e-mail address of the automatic reply is
{PrimarySmtpAddress}
e.g. email address removed for privacy reasons
Additional explanation:
- In both cases is the recipient e-mail address "email address removed for privacy reasons"
- The behavior can be traced also in the message trace log in our Exchange on-prem
- The behavior can be reproduced in the same setup in another tenant
- The behavior can be reproduced by enabling/disabling "Turn on sending from aliases"
In my opinion, the expected behavior should be that an automatic reply is always sent from the PrimarySmtpAddress
Is this behavior "by design" / a bug or miss I something in our configuration?
Does anyone also have this issue and already found a solution?