Email feels permanent until the computer dies. With older-style mail accounts that download messages (POP3), the server may delete its copy once your program has it, and your computer then holds the only one. High Desert's agreement describes email this way. This guide shows how to back it up, with steps from Microsoft and Apple.
Takeaways
- High Desert's agreement says email must be downloaded to a desktop application and that HDISS makes no warranty regarding emails retained on its server.
- Outlook exports to a .pst file; by default it downloads only the past year of email, so set the sync slider to All first.
- Apple Mail exports mailboxes in mbox format.
- Keep the export on a different drive or cloud account from the computer, and do it on a schedule.
Why is a backup needed?
High Desert's service agreement states that email service is limited to HDISS customers, that all email processed by the HDISS email server must be downloaded to a desktop application, and that HDISS makes no warranty regarding emails retained on the server. In plain words, the copy in your mail program is the copy you rely on. If the computer fails, is stolen or is replaced, mail that was only there is gone.
Our guides on POP3 and IMAP and keeping email when you change devices explain why. The fix is a regular export that you control.
Outlook: export to a .pst file
Microsoft's support page says that in classic Outlook for Windows you choose File, then Open & Export, then Import/Export; then Export to a file, Outlook Data File (.pst), pick the account or folder, include subfolders, and browse to where to save. In the new Outlook, the path is Settings, then Files, then Export. Microsoft notes that by default Outlook is set to download email for the past one year, so to export everything, open Account settings, Account Name and Sync Settings, and move the slider to All before you export.
You can add a password to the file. Save the .pst on a separate drive or folder you back up, and keep the date in the file name. The Outlook for Microsoft 365 article shows how to set up the account.
Apple Mail: export mailboxes
Apple's Mail User Guide says you can export mailboxes in mbox format: select one or more mailboxes in the sidebar, then choose Mailbox, then Export Mailbox, and pick a folder to save into. Mail saves each as an .mbox package. To bring one back, use File, then Import Mailboxes, and choose Apple Mail as the source when the mailbox was exported from Mail. See the Apple Mail article for the account settings.
Other programs, such as Thunderbird, Gmail's fetch tool and Windows Mail, have their own export or profile-copy features; look in the program's help for export or backup.
How often, and where to keep it
Monthly is a sensible rhythm for most people, weekly for a business. Put it on the calendar. Keep two copies: one on an external drive and one in a cloud folder or at another location, following the 3-2-1 idea in the backup guide. Test one restore by opening the export on another computer, because a backup you cannot open is not a backup.
Remember that a .pst or .mbox file can be large. A mailbox of several gigabytes is common, so copy it to cloud storage over a quiet evening; see the backup data guide.
When you move on
Before you change computers or providers, export first, then set up the new account. When you leave a mail service, remember that addresses on the old domain may stop working, and tell your contacts. Our email on your own domain guide describes an address you control. For help with an account's settings, call 775-575-9593 any day from 9 to 5.
If you are weighing providers, put your address through the check form first. A person studies the line from the closest tower to your roof and rings you back.
Sources
- support.microsoft.com/en-us/outlook/export-emails-contacts-and-calendar-items-to-outlook-u (Microsoft Support, Export emails, contacts, and calendar items to Outlook using a .pst file, read 10/15/26)
- support.apple.com/guide/mail/import-or-export-mailboxes-mlhlp1030/mac (Apple Support, Import or export mailboxes in Mail on Mac, read 10/15/26)
- hdiss.net/terms-of-use/ (HDISS Service Agreement V 1.12, section 4.B, read 10/15/26)