GreenNet mailboxes have a sizeable capacity of 2GB (2048 MB), equivalent to something of the order of ten thousand emails. Even this space can fill up when email is not deleted from the server for a few months. 

When the mailbox is full, the mail will not be delivered, and senders will receive a bounce message including:

: can't create user output file.

GreenNet mailbox owners will receive a warning email when the mailbox usage exceeds 60% of capacity, and further reminders at 80, 85, 90, 95 and 98%, indicating that action should be taken. This may involve setting up an email program to archive older mail via POP to the local computer, deleting larger messages, or moving email to another online folder.

If you want to check the detail of your current mailbox usage, log in to SquirrelMail and click the ‘Folder Sizes’ link on the left-hand menu. If you have let the usage in your GreenNet inbox get above 90% and want to check if any messages have bounced in the last week, please ask us.

It may be useful to be aware of the size of certain messages (some email programs don’t by default show this, but you can usually set the program to display a size column in the inbox). Large photographs, and PDFs and documents containing photographs or high-resolution logos can often be from 1 MB to 10 MB, which and fill up the largest mailbox, so it’s best to remove these once they are received. These messages are larger than ideal: a typical size limit of an email is 10M (which because of the way files are encoded works out at about a 7.4MB attachment) – GreenNet’s limit on a single message is currently 34M (25M attachment), but for finished documents sent to multiple recipients, the sender could consider ways of keeping file size down also for consideration of people on slow connections.

See below for instructions for people downloading email with POP on how to find the setting to delete messages on various email programs on PC and Mac. Most people nowadays use IMAP or webmail rather than POP; for more on the difference between the two ways of accessing your mailbox, see this article on IMAP. The account settings in your email program will usually show the type of connection as POP3 or IMAP4.

Webmail, and email programs using IMAP

If you have set your email program to access your GreenNet mailbox as an “IMAP account”, or if you only use webmail because you use an email program, the solution to full mailboxes is different from the POP solutions below. You could do any of:

  • create additional IMAP folders (in webmail or in your email program), and have a regular practice of moving any messages you want to save to those and deleting anything else. This is probably easier to do if you are already in the habit of keeping your inbox clean, deleting or filing any incoming email after it’s dealt with; otherwise it may be a habit that’s worth developing.
  • create additional local folders, and move old messages to those. This means you can keep an archive of past email on your computer, which won’t be accessible from elsewhere.
  • some IMAP clients, like Thunderbird allow you to set an automatic deletion after a certain period, but there isn't currently a way to send messages to the Archive folder automatically.
  • you could create a POP account just to archive old email. This may have a drawback in that it clears the “New” flag on each message (so you may find it harder to see what you’ve read in webmail).

Email programs using POP

If you are accessing email regularly from more than one device, decide where you want to automatically archive older messages. This typically will be a desktop or laptop with a lot of GB storage free (rather than a phone with limited capacity for storing offline messages). This primary “archiving device” has the email program that you want to set to delete messages from the server after a period of time (usually about a month, but maybe a week if you frequently get multi-megabyte attachments). If you only usually use one system to read email, obviously that would be the archiving device. If you stop using the primary device to download and delete email, you will need to choose a different one and configure that the remove older email instead (or manage mailboxes with IMAP as described above).

Mozilla Thunderbird / Netscape 6/7

In the ‘Mail & News’ window, go to the ‘Edit’ menu, choose ‘Mail and Newsgroup Settings’. Click on ‘server settings’. Ensure ‘leave messages on server’ is not ticked (or at least that delete when moved from Inbox is ticked if you keep your inbox small.)

Outlook Express / Windows Mail

Go to ‘Tools’, then ‘Accounts’, then select your GreenNet account (often called Click the ‘Properties’ button, then choose the ‘Advanced’ tab. Ensure that ‘Leave a copy of messages on server’ is not ticked, or if it is, that ‘remove from server’ is set to a reasonable period.

Outlook 2010/2013

Go to the ‘File’ tab, then ‘Account Settings’, then select your GreenNet account (probably marked default or Click ‘Change’, then ‘More Settings’ then the ‘advanced’ tab. Towards the bottom you should see an option to “remove from server after” x days. Tick this option, and select to keep 1 or 2 weeks’ email. Alternatively untick ‘Leave a copy of messages on the server’.

Outlook 2003/2007

Go to ‘Tools’, then ‘E-mail Accounts’ and choose ‘view or change an existing email account’ and ‘Next’, then select your GreenNet account (probably marked default or Click ‘Change’, then ‘More Settings’ then the ‘advanced’ tab. Towards the bottom you should see an option to “remove from server after” x days. Tick this option, and select to keep 1 or 2 weeks’ email. Alternatively untick ‘Leave a copy of messages on the server’.

See this Microsoft article for more explanation.

If you are using IMAP, a simple solution is just to move email to another folder. Alternatively, create an additional POP account with the same settings, and set it to delete email as above. If you see a lot of deleted messages crossed-out, you may want to “purge” these, by going to Edit > Purge > Purge Marked Items in Inbox.

Eudora 5-7 for Windows

Go to the ‘Tools’ menu, then ‘Options’, then the Incoming Mail icon. Untick ‘leave mail on server’, or set it to delete after (say) 14 days.

Apple Mail (Mac OS X) – POP

Open Mail. Go to the ‘Mail’ menu, then ‘Preferences’, then choose ‘Accounts’ along the top bar. Choose your GreenNet account, and then click the ‘Advanced’ tab. Make sure ‘Remove copy from server after retrieving a message’ is ticked. Either set the drop down box to ‘Right Away’ or to say ‘After one week’.
 remove messages after one week

(If there is no ‘Remove copy from server’ option, you probably have mail set up to use IMAP, not POP. As mentioned above, delete some messages from the inbox, or move them to another folder, either on your Mac, or another IMAP folder. You may also need to expunge/“erase” deleted email – see below.)

iPhone/iPad/iOS Mail

Generally, you might want to consider archiving on a desktop device: for more information see the explanation on the Apple site. If you now only access email via POP on iPhone or iPad, you can set the iPhone default of deleting after one week (Apple only give other options of “one day” or “one month”). Go to Settings > Mail, Contacts, Calendars. Tap your GreenNet email account, then Advanced > Remove (on older phones, this may be called “delete from server”). Choose “After one week” (the iPhone default). Tap Done.

Entourage for Mac

Open Entourage. Go to the ‘Tools’ menu, then choose ‘Accounts’. Click on the Mail tab. Double-click on your mail account in the Accounts list.

Click on the Options tab. Untick the box to the left of “Leave a copy of each message on the server”, or make sure that you have “delete messages from server” after (at most) 14 days. Untick the box to the left of “Partially receive messages”, or if you really need this, confirm that you want to delete messages from the server when you have downloaded them.

Click the OK button.

Eudora 3 for Mac

Go to the ‘Special’ menu, then ‘Settings’, then the Checking Mail icon. Ensure ‘Leave on server for … days’ is not ticked, or at least a non-zero number is entered.

IMAP on Apple Mail (Mac OS X)

If your Mac Mail account settings show as IMAP, and although you think you’ve deleted messages you still getting warnings about your mailbox filling up, then you may also need to set to expunge or “erase” deleted messages regularly.

Go to the ‘Mail’ menu, then ‘Preferences’, then choose ‘Accounts’ along the top bar. Choose your GreenNet account, and then click the ‘Mailbox behaviours’ tab. In the bottom ‘Trash’ section, you should see the final option ‘ Permanently erase deleted messages when ‘. Apple doesn’t recommend ‘Never’ there; furthermore, if the option reads ‘Quitting Mail’, then the server mailbox may continue to fill up if you leave your computer permanently on and never close Mail. Try changing the option to ‘One day old’. You can erase the messages immediately by finding the menu item Mailbox > Erase Deleted Items and choosing your GreenNet IMAP account. For more, see here.

Mail servers such as VPOP3

Microsoft SBS Exchange 2000 server officially doesn’t support leaving messages on the server in the POP3 connector – and if you already have Exchange and a static IP you could set up a webmail system for archiving (which in the open source world could be done with SquirrelMail and Postfix/Exim).

In the VPOP3 mail server, 5 days is quite common, but there are many large messages for multiple workers, this may be too much. The setting can be altered under VPOP3 > External Mail > In Mail > Incoming POP3 settings > Leave Messages on Server. If you are using download rules, you should also check Utilities > Misc Settings > Basic Tweaks > Query Download Delay.


The purpose of these ‘keep messages on server’ options is so that you can set your main email program to keep, say 1 or 2 week’s worth of email, which you can then read when away from your current computer. This can work well so long as a reasonable limit for keeping messages is set. You could also save specific emails for later view by setting up an IMAP folder, and dragging them there, although IMAP is often not suitable where there is dial-up or an unreliable connection.