What to do when youâre over quota.
Thatâs a synthesis of several related questions that all boil down to this:
The inbox thatâs empty isnât the inbox that matters.
Understanding this means learning a little about how email makes its way to your desktop.
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Inbox Full?
If you use a desktop email program like Microsoft Officeâs Outlook or Thunderbird, you have two options when fetching email: download the email and remove it from your providerâs server, or download a copy of the email, leaving the original online. In the latter case, the email can collect, exceeding your email providerâs limitations, regardless of whatâs happening on your PC. Solutions include manually deleting email from your providerâs server, switching to webmail so you always see whatâs there, or changing your email programâs configuration to automatically delete email online after itâs been downloaded.
The path email takes
When an email is sent to you, itâs actually sent to the email servers of your email service provider. For example, if you use Outlook.com (formerly Hotmail), when someone sends you an email message, that message is placed into your mail folders, which are kept on Microsoftâs Outlook.com server.

Until you do something with it, email continues to accumulate on your email service providerâs server. Eventually, you run out of room.
Downloading your email
When you connect to your email service using an email program installed on your computer, email is downloaded to your machine.

Generally, all email received since the last time you checked is downloaded in bulk. You can read and interact with the messages using your PC.
Downloading also means either of two things:
- Downloading all the newly arrived email and then deleting them from your email server.
- Downloading all the newly arrived email but leaving them on your email server.
The first is common if you have only one computer on which you want to deal with email. Itâs the default configuration that most email programs use when configured to use the POP3 email fetching protocol.
The second, however, has become more common, because we now tend to deal with our email on a variety of devices.

Downloading email and deleting it from the server would mean that the email is available only on the device that downloaded it. Instead, email programs are now more often configured to download or view the email, but not delete it. This is the behavior of the IMAP email access protocol.
This means all other devices wanting to access that same email can access the email stored on your email service provider.
Email limits and quotas
The big problem with leaving email on the server is that servers impose limits, often referred to as quotas. Youâre allocated only so much space to store your email on the server.
When you hit that limit, the email service stops accepting email for you. It will, instead, take one of two actions:
- Silently delete the email.
- Send a bounce message back to the sender.
In the latter case, the bounce will say something like âinbox fullâ, âmailbox fullâ, or âquota exceededâ.
The bottom line, however, is the same: youâve run out of space and wonât be getting any more email until you free some up.
Confirming the problem
In your specific case, the inbox on your PC is empty, but your email service thinks your inbox online is full. That means email has been accumulating online and not getting deleted.
The best way to check is to use your email serviceâs webmail. Thatâs how you can see exactly what your email service provider has stored online for you.

Using a web browser doesnât download or copy your email anywhere â it simply accesses it directly from your email providerâs servers. Using this approach, you can see exactly what the email service thinks you have.
My guess is thereâs a lot of email stored there that you didnât realize had been kept.
Now you can decide what to do with it â which typically means deleting it (since youâve presumably already dealt with it at some point in the past on your PC).
Fixing the problem
When you use a desktop email program, there are three possible common configurations for downloading1:
- IMAP: leave everything not deleted on the server so all devices can access it.
- POP3: download everything and delete it from the server, leaving it accessible only on the one PC.
- POP3 with âleave a copy on serverâ enabled: download everything, but leave the messages on your server so other devices can at least see them as well. Email is not synchronized across devices.2
With IMAP, if you delete something on your PCâs inbox, itâs deleted online as well. Everything is kept synchronized. This is unlikely to be your configuration, since you indicated youâve deleted lots of emails from your inbox in an attempt to make room. Had you been using IMAP, they would have been getting deleted online as well.
With normal POP3, email is downloaded and deleted from the server. This is unlikely to be your configuration, since by default POP3 deletes everything as you go.
POP3 with âleave a copy on serverâ is probably your current configuration. Itâs easy to forget that this is your configuration since it looks just like normal POP3 access, except that email continues to accumulate on the server.
There are four ways to fix this:
- Switch to default POP3, and let the email be deleted from the server. This is perfect if you read email on only one device.
- Many email programs have an option in conjunction with âleave on serverâ that says âdelete after X daysâ. Select an appropriate value for âXâ â say a month â and let the email cleanup happen that way.
- Switch to IMAP. Using IMAP, youâll have more control over whatâs stored on the email serviceâs server, since when you delete a message on your PC, itâll be deleted on the server and everywhere else. The only drawback is that all the email you want to keep will continue to be kept on the server as well. This includes all folders. If this becomes a problem, youâll need to figure out how your email program handles local folders â folders that are on your computer only â and move some of your messages there. Moving them out of IMAP folders will remove them from the server as well.
- Switch to webmail. This doesnât free up space in and of itself, but it means youâre operating on the serverâs repository of your email, will see clearly how much is stored, and clean up appropriately.
If you want to continue using an email program on your PC, I recommend option 3 if at all possible. It really does make managing email across multiple devices significantly easier. Personally, I live in option 4 â the Gmail web interface, in my case.
Email is surprisingly complex
As you might have gathered by now, managing email can be surprisingly complicated.
Learning just a little about how and where email is stored will not only help you understand the dreaded âinbox fullâ message, but give you some solid ideas on how to deal with it.
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When you set up an account for POP3 access in Thunderbird, there is or was an option to delete the mail from the server when you delete it in Thunderbird. I havenât used POP3 in years so Iâm not sure if that feature is still there. I think most email programs have that option.
âThere are four ways to fix this:
Switch to default POP3, âŠ
âleave on serverâ with auto deleteâŠ
Switch to IMAPâŠ
Switch to webmailâŠâ
I will add a 5th way â Use a service like Gmail (or other similar one) that offers a huge storage amount and occasionally clean things out as needed. The advantage of occasionally using the web interface is that you can also use it for training the spam filter.
That would be âswitch to webmailâ.