I’ll be adding to this as I continue to work with O365, but for now I have two things I usually do for every tenant:
First, connect to O365 via Powershell. If you don’t know how, please see my recent blog post
Disable “Clutter” feature for all mailboxes:
Get-Mailbox -Filter * -ResultSize Unlimited | Set-Clutter -Enable $false
Raise email message size limits for all mailboxes (and mailbox plans):
Get-Mailbox -Resultsize Unlimited | Set-Mailbox -MaxReceiveSize 75MB -MaxSendSize 75MB
Get-MailboxPlan | fl name,maxsendsize,maxreceivesize,isdefault
Set-MailboxPlan ExchangeOnlineEnterprise-XXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXX -MaxSendSize 75MB -MaxReceiveSize 75MB (use mailbox plan name from previous command)
Disable password expiration:
Log into O365 web admin portal (https://portal.office365.com)
Go to “Service Settings” –> “Passwords” and select “Passwords never expire”