An e-mail is received for a first user's e-mailbox that increases accumulated storage volume of e-mails beyond a capacity limit. Available storage space indications are accessed for e-mailboxes of other users designated as overflow e-mailboxes. Overflow e-mailbox designation indicates agreement by a user to loan at least a portion of their e-mailbox. Responsive to indicated availability of storage space therein and cost of access, one of the overflow e-mailboxes is selected and a pointer thereto is stored for the first user pointing to the overflow e-mailbox. Thus, space in the first user's e-mailbox is reduced by using a loaned portion of storage space in the overflow e-mailbox in lieu of space in the first user's e-mailbox. Users may receive credit for loaning or be charged for using overflow e-mailbox space. E-mailboxes may be polled for space availability, so e-mail may be transferred from overflow e-mailboxes to the first user's e-mailbox.