Booth: 12. November 2025
If your email inbox on the web server overflows, you do not have to delete your emails; instead, you can simply archive them.
We will show you how to do this step-by-step using Apple Mail as an example. The basic principle also applies to other email programs such as Outlook, Thunderbird, or eM Client. Note: With POP3 accounts, emails are usually stored locally; the storage problem primarily arises with IMAP.
Why is My Email Inbox Becoming "Full"?
With today’s common IMAP accounts, emails and their attachments remain permanently stored on the server and are synchronized between devices. As a result, the occupied storage space on the mail server continuously grows – especially with large attachments such as photos, layouts, videos, or PDFs. In creative professions or project-oriented teams, the mailbox can therefore quickly reach its limits.
These limits are technically and contractually defined: Each email provider only provides a certain amount of storage, which depends on the respective plan. Once this limit is reached, no new messages can be received until space is created or the mailbox is enlarged.
Why not Simply Delete Old Emails?
- Business emails are subject to legal retention requirements (GoBD, HGB). Invoices, offers, and other business-related messages must be retained for several years in many cases – regardless of the mailbox or device.
- Self-employed individuals and freelancers are also generally obliged to retain tax-relevant correspondence. Premature deletion can lead to disadvantages during a tax audit.
- Private or irrelevant emails may, of course, be deleted – the crucial point is to securely archive business-relevant emails, not to leave them in the inbox.
Why Archive Emails Instead of Simply Continuing to Use Them?
Server space is limited – especially emails with large attachments (photos, layouts, PDFs, etc.) can quickly fill up storage, particularly in creative professions. However, even if there is still space available, regular archiving is worthwhile:
- Emails on the server remain permanently online and are therefore potentially vulnerable (e.g., in case of hacked passwords or compromised servers).
- Very large mailboxes can slow down synchronization because more emails and attachments need to be synced between devices.
- Local archives are available offline, regardless of the provider, and can be secured in backups.
- Only local archiving reduces occupied server storage and protects sensitive data from unnecessary permanent retention in the cloud.
The following text simply explains how to free up space on your email server. Because this problem continues to exist even if you do everything right with statutory data backup, because it retrieves emails from the server but does not delete anything there.
Apple Mail (macOS Sonoma / Sequoia)
1. What Apple Means by “Archive”
The function “Archive” or “Move to Archive” creates a special mailbox called “Archive” on the server. When a message is archived, it remains stored online – just in a different folder. These emails continue to sync with iPhone, iPad, and other devices. This does not save server storage space; it merely serves for organization.
Note: Since archived emails in Apple Mail remain online, they are generally exposed (e.g., in the event of compromised access). A local archive is therefore not only space-saving but also more privacy-friendly.
2. Create a True Local Archive
- Menu “Mailbox → New Mailbox…“
- Location: “On My Mac“
- Name: e.g., ARCHIVE 2024
- The new mailbox appears in the left column under “On My Mac”.
- Select old emails and move them to this local mailbox.
As a result, the emails are deleted from the server and are now exclusively on this Mac. They remain available and searchable offline. The emails are backed up in your computer backups (e.g. Time Machine).
Note: After deleting the emails from the server, they are no longer available on other email clients (e.g. on mobile devices), but only on this Mac. This is usually intentional, as it also frees up valuable storage space there.
Not understood? Please read the illustrated older version of our instructions (see below). This is very detailed and explains each step in detail.
3. Automatic Moving with Rule (Optional)
- Menu “Mail → Settings → Rules → Add“
- Condition: “If Mailbox is Archive“
- Action: “Move to Mailbox On My Mac → ARCHIVE 2024“
This ensures all archived emails are automatically stored locally, reducing the server load.
Detailed Instructions for Older Apple Mail Versions (before 2024)
Check the Type of Email Account in the Email Program (Required once)
First, go to the account settings of Apple Mail (menu “Mail” > “Settings”). There, find the email account that you want to archive. First check if the protocol “IMAP” is preset there in the settings, this is very important! If you find out that you are using a “POP” type email account, please → continue reading here, because the following instructions refer exclusively to “IMAP” type accounts.
1. Create local archive mailbox (required once)
From the “Mailbox” menu, select the “New Mailbox…” option: 
A dialog box will appear.
- For “Location”, select the “Local” option
- Assign a meaningful name, e.g. “ARCHIVE – Mailbox name – Receive”, where Mailbox name represents the name of the server mailbox you want to archive. This way you can quickly find the archive again if you have multiple archives. (” – Receiving” we still hang on it, since one could archive sent e-mails after the same method, these would get accordingly the ending ” – Dispatch”).
A new folder has been created in the “Local” directory: 
Nothing to see? Then the new local mailbox may be hidden. Then simply hover the mouse over the word “Local” (in the left mailboxes column in Apple Mail). To the right of it you will then see the word “show” in gray, please click on it.
Tip: By the way, clicking on the plus sign to the left is another way to create a new local mailbox directly at this point.
2. Check the disk space used on the server (regularly)
- In the left sidebar of the program window, under the heading “Mailboxes”, expand the “Inbox” folder if collapsed (click on the small gray triangle on the left)
- Right-click on the desired email account.
- Select “Account information” in the popup menu at the bottom of the screen.
You will then see a new window showing the amount of memory used:
Now you have a good overview of how much storage space is still free and whether you need to archive if necessary. Now close this window again.
3. Perform local archiving (regularly)
Now you can move the mails you want to archive to the new folder you just created:
- In the list of displayed received emails of this mailbox, click the “Sent” tab at the top of the table header. The new emails should now be at the top and the old ones at the bottom, otherwise please click “sent” again. (If “sent” is not displayed, please right-click on the table header and select the display of the “sent” column).
- So the old emails are now at the bottom. Therefore, scroll all the way down and select the bottom email. Then scroll further up back to the first email from which archiving is to be started. Click on these with the Shift key held down. This selects all emails between this email and the lowest email.
- Now drag the selected emails to the new local account ….. and WAIT.
- Apple Mail now moves the emails from the server and also moves all email attachments. Therefore, this may take some time. Please let Apple Mail run and work for a while (e.g. 5 minutes) and do not quit! How fast Apple Mail rearranges depends on the amount of moved emails, attachments and internet speed.
4. Done!
Congratulations, you have just created your first local email archive! For later archiving for this email account, perform only the last step (“4 Use the local archive”).
Instructions for e-mail accounts of the “POP” type
If you still use the old e-mail protocol “POP” (sometimes also called “POP3”), you have already backed up all e-mails locally in the e-mail program, as long as they are not deleted there. The storage problem on the server is also quite easy to resolve: Go to the account settings of your email program. First check whether the “POP” (or “POP3”) protocol is set there. Then select there: “Delete emails permanently from server after XX days” where “XX” is usually 1 week. In Apple mail, the setting looks like this:
Outlook (Windows / macOS / Microsoft 365)*
Outlook offers two archiving options: an online archive (server folder, no storage savings) and a local archive in a data file (.pst or .olm).
How to archive locally and save server storage:
- “File → Info → Tools → Archive…“
- Select account or folder.
- Specify the storage location for the
.pstfile and start.
Outlook moves the emails to the local file and removes them from the server.
Thunderbird (Windows / macOS / Linux)
Thunderbird can redirect “Archive” directly to local folders.
- “Settings → Account Settings → Copies & Folders“
- Under “Archive save as”: Select “Local Folders“.
- Save, then use the “Archive” icon.
Archived emails are moved to local folders and deleted from the server. This immediately reduces online storage usage.
eM Client (Windows / macOS)
eM Client offers simple, automatic archiving to local folders.
- “Menu → Settings → Email → Archiving“
- Activate archiving and choose a time period (e.g., older than 6 months).
- Destination: Set to “Local Folders“.
Older emails are automatically stored locally and removed from the server.
MailStore*
MailStore Home (for private use) and MailStore Server (for businesses) archive emails from IMAP, POP3, Exchange, Outlook, or Thunderbird. The emails are stored locally or centrally and remain searchable. After archiving, they can be automatically deleted from the server, freeing up storage space.
Cloud mailboxes (Gmail, iCloud, Outlook.com, GMX, Web.de)*
For cloud mailboxes, “Archiving” usually just means moving emails from the inbox, but keeping them online (e.g., in Gmail’s “All Mail” folder). This does not free up storage space. If you truly want to offload emails, use programs like Thunderbird, Outlook, or MailStore and then remove the archived emails from the server.
Legal Disclaimer
We have no agreements with any of the software providers mentioned, and we have not tested all products ourselves. The information is based on the published information of the respective providers.
*Particularly the information on Outlook, Mailstore, and cloud mailboxes is AI-generated, as we do not use these programs. If in doubt, please read the respective instructions. These texts appear plausible upon careful review and are therefore included for completeness.
The information provided here is for general guidance and does not constitute legal advice. For questions regarding retention obligations or GDPR compliance, please contact your tax advisor or data protection officer.
