Format Atlas

Guides

Verifying messages after an email migration

After choosing a format, record scope and metadata, then compare bodies, attachments and counts in a trial import before migrating the working mailbox.

Which format should you choose?

Choose by the role each file plays in your workflow.

  • Fix the scope and retain originals
  • Compare bodies, headers and attachments
  • Reconcile in an isolated import destination

Fix the scope and retain originals

Record accounts, folders, date range, counts and export settings, and retain the source mailbox. Exchange files may not preserve folders, labels or read status on their own. MBOX separators and escaping vary between implementations; check exporter and importer compatibility.

Compare bodies, headers and attachments

Select multilingual, long, HTML and plain-text messages, including embedded images and attachments. Compare sender and recipients, subject, body, attachment names and decoded content. Distinguish the Date header from the application's received time, and check whether external image loading masks missing content.

Reconcile in an isolated import destination

Import into an empty test destination and check scoped counts, omissions, duplicates, folder mapping and display. Record differences and unsupported fields; agree on duplicate handling before repeating the import in production. Readability alone proves neither full metadata preservation nor authenticity.

Formats to consider

EML

Good for: Checking individual message bodies, headers and attachments

Less suitable for: Passing a bulk migration after displaying one message

MBOX

Good for: Trial migration of multiple messages between compatible implementations

Less suitable for: Inferring separator and escaping compatibility from the MBOX extension

MSG

Good for: Checking items in a compatible Outlook environment

Less suitable for: Assuming non-mail Outlook items can all be migrated to EML

Before you export

  • Messages and attachments can contain private or confidential data. Share only the required scope and inspect without automatically executing suspicious attachments or external connections.
  • Keep originals, an inventory, checksums and conversion history. A PDF viewing copy does not replace the original message structure.

Related comparisons

EML vs MBOXEML commonly stores one email message. MBOX groups multiple messages in a mailbox file. Choose by the unit you need to preserve or move.MSG vs EMLMSG stores Outlook items and can represent more than email, including appointments and contacts. EML is commonly used to save or transfer one internet email message at a time.MBOX vs MSGMBOX typically stores multiple email messages in a mailbox file, while MSG is commonly used for an individual Outlook item. Choose according to the unit being migrated and the destination application's import support.

Guides

Choose a format for saving or migrating emailChoose according to whether you need one message, a whole mailbox, or an Outlook item, and back up the source before importing.Verifying calendar and contact data with a trial importAfter choosing a format, check time interpretation, recurrence, contact fields and duplicate handling in a test environment before migrating existing data.

References and specifications