Just a quick one-liner for exporting usable info about all mailboxes. Be sure to adjust your domain controller (or leave it out if in a single domain environment).
get-mailbox -ResultSize unlimited -DomainController ADC1 | Select-Object DisplayName,PrimarySmtpAddress,ExchangeUserAccountControl,RecipientTypeDetails,ServerName,Database,ProhibitSendQuota,ProhibitSendReceiveQuota,UseDatabaseQuotaDefaults,IssueWarningQuota,MaxSendSize,MaxReceiveSize,DeliverToMailboxAndForward,HiddenFromAddressListsEnabled,WhenChanged | Export-CSV C:\mailboxes.csv
Returns some good info about mailbox size quotas, send/receive limits, mailbox type, forwarding and address book status.
