Does the 'Send customer replies to' address fix spam problems?

No. It only controls where replies go. The From address stays the booking mailbox's primary SMTP address, so filters judge the same sender as before.

Do I need to recreate my booking page to change the domain?

No. An admin can change the existing mailbox's address in Exchange Online PowerShell. Recreating the page is only a fallback if nobody can run PowerShell.

Can customers mark the sender as safe instead?

They can add it to their safe senders, but that fixes one inbox at a time. Fixing the sender domain and its authentication helps every recipient.

Answer · Notifications

Why are Microsoft Bookings emails going to junk or bouncing?

Last updated 24 September 20264 min readPart of Emails, reminders and SMS in Microsoft Bookings5 sources

The question people ask

“Why are Microsoft Bookings confirmations going to junk or bouncing?”

Asked in Microsoft Learn (opens in a new tab), Microsoft Learn (opens in a new tab), Microsoft Learn (opens in a new tab), Microsoft Learn (opens in a new tab) and Microsoft Learn (opens in a new tab)

Short answer

In most cases the cause is the sender. Every shared booking page is an Exchange mailbox, and unless an admin changed it, that mailbox sends from your tenant's default yourtenant.onmicrosoft.com domain. The Microsoft Learn best-practices article for shared booking pages warns that the default domain "may cause Bookings email notifications to land in recipients' spam/junk folders". The fix has two parts: give the booking mailbox an address on your own domain, and make sure that domain passes SPF, DKIM and DMARC. This page covers the diagnosis and the authentication side. The PowerShell steps for the address change are on changing the Bookings sender address.

Read the symptom first#

What you see	Likely cause	Where to go
Emails arrive in junk, From ends in `onmicrosoft.com`	Default-domain reputation	Change the sender, then check authentication below
Staff see a bounce with `550 5.7.1` ("Sender address rejected" or invalid sender)	The receiving server refused the sender	Authentication checks below
Your own gateway rejected or quarantined the message	A transport rule, connector or third-party filter in your tenant	Mail flow rules below
From is your domain, but mail still goes to junk	SPF, DKIM or DMARC incomplete for that domain, or the recipient's own filter	Authentication checks below
Some customers get nothing, and there's no bounce	A settings or address problem, not spam	Customers not receiving emails

The Microsoft Q&A threads behind this page show all of these. A 2023 thread (10 "same question" votes) was fixed by moving off onmicrosoft.com. A 2025 thread about 40+ customers' reminders going to junk got only generic advice. A 2025 thread with 550 5.7.1 "Sender address rejected" was resolved by fixing the sender domain and its SPF and DKIM.

Check SPF, DKIM and DMARC for the sending domain#

Moving to your own domain only helps if that domain authenticates Microsoft 365 mail. Microsoft calls the three standards "interdependent building blocks that work together", so set up all three:

SPF: the domain's SPF TXT record includes Microsoft 365 (include:spf.protection.outlook.com) as an allowed sender.
DKIM: DKIM signing is turned on for the custom domain in the Microsoft Defender portal, with both CNAME records published in DNS.
DMARC: a DMARC TXT record at _dmarc.yourdomain so receivers can check that the From domain lines up with SPF or DKIM.

If staff already send everyday email from the same domain without junk problems, these are probably in place. Confirm it with a real booking rather than assuming.

Test with a real booking#

Book a test appointment on the public page with a Gmail address and an Outlook.com address.
In Gmail, open the confirmation and choose Show original. The header summary shows SPF, DKIM and DMARC as PASS or FAIL, and the domain each one checked.
If DKIM shows onmicrosoft.com instead of your domain, or DMARC fails, fix the DNS records for the domain before anything else.
Repeat after each change. DNS changes can take time to spread.

Check your own mail flow rules#

Several bounce threads, including a widely read 2020 one (30 "same question" votes), traced the problem to the organisation's own Exchange transport rules, which blocked or rewrote mail from the onmicrosoft.com sender. Ask an admin to:

Run a message trace in the Exchange admin center for a recent confirmation to a failing recipient.
Look for a transport rule, connector or third-party gateway that rejects, rewrites or quarantines mail from the booking mailbox.
Read the bounce text. A 550 5.7.1 from the recipient's server points at sender authentication. A rejection from your own gateway points at a rule.

What you can't change#

As of September 2026:

The From address isn't a setting in Bookings. "Send customer replies to" on Business information only sets reply-to.
The email template isn't editable, so you can't strip content a filter dislikes. You can only add text per service. See customizing the confirmation email.
Microsoft doesn't document deliverability monitoring for Bookings. Message trace in Exchange is the only built-in tool.

Reminders come from the same mailbox, so they land in the same place as confirmations. If reminders are your main worry, the no-show reduction guide covers delivery testing as part of a reminder plan.

BookingsXP is independent and not affiliated with or endorsed by Microsoft.

Questions people also ask

Sources

Microsoft Learn: Best practices shared bookings (opens in a new tab) · learn.microsoft.com
Microsoft Learn: Bookings app admin (opens in a new tab) · learn.microsoft.com
Microsoft Learn: Custom domain support (opens in a new tab) · learn.microsoft.com
Microsoft Learn: Bookings faq (opens in a new tab) · learn.microsoft.com
Microsoft Learn: Email authentication about (opens in a new tab) · learn.microsoft.com