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ProtonMail Mailbox Full? 5 Proven Ways to Reclaim Storage Space

  author
Jamie Kaler   Contribution
Rollins Duke
Rollins Duke  Approved By
Published On June 4th, 2026 • 7 min read

Encountering the ProtonMail storage full warning is frustrating, especially when crucial mail messages cease to arrive, or email attachments stop uploading. As mailboxes grow in size with heavy emails, files & folders, the available storage space quickly reaches the threshold limit. Here, in this blog, we will be discussing manual operations of cleaning up the space and also check out a pro tool to back up data for managing mailboxes better.

Imagine opening the inbox, only to find new emails no longer coming in. Attachments won’t upload either. A quick storage check reveals the cause: ProtonMail storage is full. This situation is pretty common for people who have been storing email data, including emails, newsletters, attachments, invoices, project files, etc., in their mailboxes for years. When ProtonMail’s storage limit is exceeded, mailbox management becomes difficult.

Why Does the ProtonMail Storage Limit Issue Arise?

You are most likely to encounter the ProtonMail storage limit issue in the following scenarios:

  • A lot of old messages are still saved inside your inbox.
  • Large-sized attachment files, including PDFs, video files, & images, take space.
  • Spam folder & Trash folder are not emptied regularly.
  • Many custom folders tend to contain several archived emails.
  • Newsletters & promotional messages too gather in big numbers over time.
  • Backups aren’t maintained outside the mailbox, and thus, the heavy load.

When such situations go on for months or even years, a lot of storage space is used.

What Actually Happens When ProtonMail Storage Is Full?

When your email account reaches its threshold limit, you might experience the following problems:

  • Difficulty receiving new mail messages.
  • Issues while sending emails with heavy attachments.
  • Warning notifications from ProtonMail.
  • Mailbox sync delays start to occur.
  • Significantly reduced mailbox performance.

For these reasons, constant mailbox cleaning is crucial. Some users wonder why they are seeing such a storage full warning message even after deleting emails. Well! This is because emails in the Trash folder & Spam folder might still be occupying your storage. Permanently deleting them is seen to fix the issue.

How to Free Up Space in ProtonMail on Mac Manually?

Below are some manual methods that can help reclaim storage. Check out the manual method and also find the quick solutions with the MacUncle to clean up the ProtonMail account.

Method 1: Delete Unwanted Emails to Fix “ProtonMail Storage Full”

The easiest method of creating storage space is to remove unwanted emails. This is a totally free-of-cost way that’s even simpler to undertake with immediate storage recovery. However, it could be a bit time-consuming for large mailboxes. Also, you must be careful, as crucial emails might get deleted mistakenly, so you need to do a manual review. Follow the steps below carefully by focusing first on newsletters, marketing mailers, & old conversations:

  1. Sign in to the ProtonMail account
  2. Open the Inbox.
  3. Sort emails by date or sender.
  4. Select unnecessary emails.
  5. Click Delete.
  6. Move them to Trash.

Try the professional way: We can mass delete emails Protonmail. Check out the article and try different methods from here, and use the one that works best for the situation.

Method 2: Remove Large Email Attachments

This procedure can speedily free up a good amount of space. Email attachments are known to consume more storage space than normal email text. Doing this process would release big amounts of storage space, which will help you to organise your files better. However, this method requires you to download your files individually, and thus, managing too many email attachments could be a hard thing to do. Perform the process by doing the steps mentioned below:

  1. Log in to Proton Mail.
  2. Search for emails with large attachments.
  3. Identify messages with the largest files.
  4. Download important attachments to your Mac.
  5. Delete the emails once the files are saved securely.

Method 3: Empty your Trash and Spam

Most people forget that deleted messages still occupy storage space till they are removed forever. This simple operation gives quick space recovery, but remember that once deleted permanently, those emails can’t be retrieved conveniently afterwards. Carefully carry out the steps mentioned below to execute this procedure:

  1. Open Proton Mail.
  2. Go to the Trash folder.
  3. Review contents.
  4. Permanently delete unnecessary messages.
  5. Repeat for the Spam folder.

Method 4: Clean Old Archive and Custom Folders

Archived mails & custom folders usually contain years of saved emails. This process will enhance mailbox organisation and even lower storage consumption, but you need a careful review of your old emails while doing this. Execute the process by following the steps given below:

  1. Review your Archive folders.
  2. Check custom labels & folders.
  3. Identify outdated mail messages.
  4. Delete unwanted content.
  5. Empty your Trash folder.

Method 5: Export Important Emails Before Deleting

Before you remove any crucial emails, try creating a backup of data on your Mac. This process is essential for better data protection by reducing the risk of critical data loss. Such an approach ensures critical info remains as it is, while storage space is recovered too in this exercise. However, you need extra storage on a Mac for this, as manual export takes time. Do the steps that are described below:

  1. Identify important messages.
  2. Export and save them locally.
  3. Verify the backup.
  4. Delete the emails from ProtonMail.
  5. Empty the Trash folder.

Smart Advice: You can even take the backup using a dedicated tool backup ProtonMail emails to any different file formats, which is especially useful when dealing with years of accumulated email data. This software allows users to save mailbox data locally on a Mac before the user deletes the emails from the server. Such an approach helps in preserving crucial emails, lessening mailbox size securely, maintaining long-term email records, & also improving storage management.

FAQs

Q) Is ProtonMail storage freed immediately after deleting emails?

A) Storage is usually recovered after emails are permanently deleted from the Trash.

Q) Is it possible to back up ProtonMail email data before deletion?

A) Yes. You can export important messages to your Mac before removing them from your mailbox. The professional tool is very helpful while dealing with years of accumulated email data.

Q) Why does ProtonMail storage get full?

A) Large attachments with emails, unnecessary old mail messages, & heavy items saved in the Trash folder & Spam folder are the most common causes for this.

Q) How to free up space in ProtonMail without deleting critical emails?

A) You can export/backup crucial mail messages first, and after that, remove those from your mailbox to recover storage space. You can delete large messages, remove unwanted email attachments, and even permanently empty your Trash folder & Spam folder.

Conclusion

A ProtonMail storage full warning should not be ignored, as it affects your ability to send and receive messages. Regularly deleting unnecessary emails, eliminating big email attachments, emptying the Trash folder & Spam folder, and organising archived emails will keep your storage well under the limit. For users with heavy email collections, mixing manual cleanup methods with a professional backup tool is usually recommended.