Which first - MX records or data migration?

[TwistedHelixis]

I am in the process of migrating a small primary school over from Office 365 to G Suite.

 

I have already created the domain in G Suite as a primary, added all the users and everyone has logged in once.

 

A few posts I have read (and even Google support) seem to suggest my next stage is to migrate the emails and files over before switching the MX records, but I am wondering why this order?

 

The problem I can see is that our LA will need to update the MX record, they have already said it will not be over a weekend, and they can only give a rough time / day that it will get done.

 

So if I migrate all the emails over, those users could potentially still get emails in the old inbox until the LA update the MX record.

 

Has anyone switched MX records before migrating emails and files from the old system?

[Foresthippy]

I'd have said MX record first. Then any new mail will be delivered to g suite and you can migrate the rest in as you please.

[foofighterjim]

I'm with @jdmackay this is exactly what we did when we moved to O365. I just let everyone know that their old emails would appear within x days.

[Boredguy]

When we migrated e-mail systems, we transferred the bulk of the e-mail over prior to the MX record getting updated, but continued to sync the old mail for a few days after the migration.

 

It just depends which route you prefer.

[timbo343]

When i moved our OnPrem Exchange emails to Office365 in a weekend in summer, i moved the MX record first then wrapped up the mailboxes from the OnPrem Exchange server in a PST and exported this way.

[chaplic]

Either order works, or I tend to say "when 75% done" if it's a big migration. In your case I'd do it at the end with some adaptions so no-one will lose an email.

 

In the old world, once the mailbox is move setup a mail enabled contact to forward mail received to the gmail account

 

You'll have to either setup a temporary migration domain at the google end (my preference) or set your domain as internal relay in o365 and have a connector pointing towards google (in other words, its setup so that if mail comes into O365 and the mailbox doesn't exist, it ships it to google

 

The only challenge with both approaches is that other peoples SPF records can cause a problem and you may need to whitelist mail coming in from O365 - perhaps a gmail guru can assist with that

Edited April 5, 2019 by chaplic