The mail servers for Biology and Geosciences allow users to read mail using two retrieval methods, POP and IMAP. Generally, using POP results in copies of mail messages being downloaded to the hard drive of the computer used to read mail; once the copies are received by the POP client, the original messages are deleted from the incoming server. Reading mail using IMAP leaves the original messages on the incoming mail server. Whether you're using POP or IMAP, incoming mail for all users, both in Biology and Geosciences, is stored in space shared by everyone. When that fills up no one receives mail. It's for this reason that POP users should configure their email software to leave mail on the server for a limited period of time; how long that should be depends on the volume of mail a given user typically receives and that user's mail reading habits. It's also why IMAP users should sort their 'in' mail to other folders on a regular basis. Sorting a large volume of email into smaller chunks also improves the performance of both POP and IMAP clients. Note that additional folders created by IMAP clients on the server are added to users' home directories; home directories are also located on shared space, which limits the combined volume of mail and other data users can retain in their home directories.

When switching from reading mail using POP to using IMAP you should first determine the size of your POP client's 'in' mailbox and, at least for Eudora users, the directory used to store attachments. It's important for Eudora users to take the size of the attachments directory into consideration because some programs, Thunderbird being one, re-attach those files to the original message when mail is imported from Eudora (which stores them separately). Depending on the default behavior of the IMAP client importing mail, there is the potential for copying large volumes of email to the servers. By default Thunderbird's Import Wizard stores imported mail on the local hard drive. However, if you later copy or move imported mail to your IMAP mailboxes, you can potentially fill up the shared space used for all users' incoming mail and cause inbound mail to bounce for everyone. The available space on your computer's hard drive should exceed the size of your mail collection and attachments, ideally by at least a few hundred megabytes. The following are the default mail storage locations used by Eudora, Thunderbird, and Apple Mail:

Eudora Windows XP C:\Documents and Settings\‹username›\Application Data\Qualcomm\Eudora
OS X /Users/‹username›/Documents/Eudora Folder
Thunderbird Windows XP C:\Documents and Settings\‹username›\Application Data\Thunderbird
OS X /Users/‹username›/Library/Thunderbird
Apple Mail OS X /Users/‹username›/Library/Mail