Company Rebrand - looking for advise on what needs to change in M365/Azure

[sumo83]

Hi experts,

our company will change the name soon and I'm trying to find out what all needs to be changed and where :) .... We use M365 / Exchange Online / Sharepoint & One Drive / Azure (have VMs and storage accounts there etc..) and we are hybrid scenario with DC running in Azure

• changing primary email address - this should not be an issue - I will just register/activate new domain in M365; update proxyAddress in AD to have them synced as "alias" - once prepared, I will just make them a primary when needed
• for "primary" user name - again... I will just change it to the new one when ready

Or - when I change the "default domain" to the new one, will primary username and primary email update automatically for users?

What else needs to be modified so that we have sharepoint links, etc showing the new company name?

• I've will change "Name" in "Org Settings -> Organization Information" in M365 Admin portal
• I will change "Name" in "Microsoft Entra ID -> Overview -> Properties" (if the change in M365 admin above will not change it automatically)

Is there anything else that needs to be changed? 

Will EXISTING SharePoint links that are shared with partners, for example, be unusable after company name changes and new folders needs to be re-shared?

Appreciate your advise on this... Have still few weeks for this to happen so want to be prepared as best as I can ;)

[#2]

@sumo83 

I thought the most important thing was Domain and anything reflect on old branding such as landing page (ADFS), disclaimer (Exchange Online). etc.

[#3]

@Kidd_Ip 

yes... those should be fine.... There are however parts that I am not 100% sure about... like the below:

• renaming domain for sharepoint seems to be the most tricky here.... 
• Would that "break" existing sharing links
• is there an impact on documents in sharepoint that have links to another documents in sharepoint?
• I believe that the approach for changing mail address would be:

1. create new domain in  Active Directory Domains and Trusts
2. configure proxyaddress to include the new domain as an alias in AD (make sure it is synced)
   • can this be mass done via script or smthing?
3. on "go live" day, change default domain in M365

• will this change also primary domain for mailboxes and primary username automatically or need to do it manually for all? (if so, any script that can be used?)

the "go live" day is approaching slowly so ideally I try to find answers to these beforehand :)