Server Upgrade Question

Yes they can be reused.

If you upgrading the Windows Server OS itself then no issue as the license binds to the MAC address.

If you are moving to a fresh Windows 2019 Server then it will require deallocating on the existing machine within Setup > General > License > Padlock then inputting onto the new system via similar screen.

Great, will we be able to copy our existing WHD data over as well to the new server?

Of cause, will depend on the Database type you are using and if it resides on the same server.

Many sites who use say MS-SQL or MySQL will want to host the Data on a separate Database Server so in those cases no database move is required.

If you use PostgreSQL then the following article should help Back up and restore the PostgreSQL database using the web console on Web Help Desk 

We Utilize PostgreSQL can we install the latest version of WHD on the new server and restore the back up from on older version of WHD or is it best to mirror the version on the new server first. 

I would personally install exactly the same WHD release, restore the PostgreSQL database to make sure OK then upgrade to a later release of WHD from there.

Thank you do you happen to know from 12.7.5 the path we take to get to the most current version 12.7.10

I would personally go to WHD12.7.9 + HF1 only due to the word-wrap and embedded YouTube issues in 12.7.10.

The Installation / Upgrade Guide states you have to go via 12.7.7, this is due to the conversion from PostgreSQL 9 to Postgres 13 which is done at that stage via the "upgradeDatabase.bat" procedure.

Do you know if  12.7.7 Version supports Modern Authentication email? We Upgraded Successfully but it still showing as Basic Authentication. 

Modern Auth has been supported across all 12.7.x releases, you should see the OAUTH option available on the IMAP & Exchange/O365 Types

What has this to do with WHD, just looks like spam to get you to buy 3rd party MS keys?