Office 365 Migration help

I would suggest you start by looking at the Exchange deployment assistant see below link:

https://docs.microsoft.com/en-us/exchange/exchange-deployment-assistant

Its a click by click to help you based on your current exchange environment.

Thanks for that, I've already been through it.

I miss communicated some information, I will be moving from hosted email to 365

Can you confirm the steps to take, I was thinking something on the lines of;

1. Setup Office 365 and verify domains
2. Setup email address
3.  etc etc etc

I'm mostly concerned with the cutover, how is that done. I know its a DNS change but at what time?

the best thing to do is use a IMAP connection between your current  host email provider to o365 because it will help you avoid losing mail during the cutover. this is for migrating gmail user to o365 but it can be used with other providers also. apart from a 3rd party app this is probably the best way so that you dont loose mail during the cutover process and you dont have to create alot of pst files, unless the mailboxes are really large. the link will provided step by step including verifying domain and when to change DNS.


https://docs.microsoft.com/en-us/exchange/mailbox-migration/migrating-imap-mailboxes/migrate-g-suite-mailboxes

I'm using Migration WIZ which allows me to run multiple passes until cutover

Can you confirm the steps to take, I was thinking something on the lines of;

1. Setup Office 365 and verify domains
2. Setup email address
3.  etc etc etc

I'm mostly concerned with the cutover, how is that done. I know its a DNS change but at what time?

Brilliant info - Thanks

At what point would I point O365 to mimecast?

What is mimecast used for? Is it for filtering email or what exactly is it's place in your org in relation to mailflow if it's being used.

Its a spam filter, its used for incoming and outgoing mail

oh ok, during the DNS change you will point your mimecast to o365, so you will not need to change your external MX record if you choose to still use the mimecast instead of o365 for inbound mail but you will have to change mimecast so that it will know to point to o365 since its responsible for your inbound mail. setup mimecast to forward inbound mail to your o365 MX record you get from step 1.

Also just a quick note, even though you will not need to change your external DNS record since it will still point to mimecast, you will need to need to change your external autodiscover and SPF records so that they point to O365, and you will get those records also from O365 during step 1.

If you have onprem exchange 2010 sp3 or higher, 3rd party tools are a waste of time and money. Hybrid move is the way to go, and allows for a 0 downtime migration. Also, if you're only using mimecast for spam filtering, you should know that O365 has built in spam filters. They are light on features for spam control, and that's the only difference between vendors at this point, so unless mimecast is giving you features you just have to have, don't waste your money.