* Don't rely on free e-mail services like Hotmail or Juno for business purposes. They don't store many messages and lack many of the features that "real" (POP3) accounts offer.

* Find out how much space your ISP gives you on its mail server for mail (this number is not to be confused with the space it gives you for your Web page). The most common limit is 10MB, but some ISPs allocate less. When you expect a large file attachment to arrive by e-mail, make sure it doesn't exceed your allotted space. If it's too large for your in-box, advise the sender to FTP the file to your site so you can download it to your hard disk. (Note: If you take this approach, you'll have to divulge your user name and password to the sender, so be sure to change your password immediately after that transaction is completed.)

* Some ISPs store only a certain number of e-mail messages --100, say -- before they start bouncing your mail. Find out whether your ISP imposes such a limit; if the limit is a problem, switch ISPs.

* For security reasons, some ISPs -- like many corporate mail servers -- forbid users to receive file attachments larger than 1MB-2MB. If your ISP has a size limit, you may be able to get an extension simply by asking for one. Note that some providers may charge you for providing that additional service.

* If a daily deluge of e-mail comes your way, download your mail at least once a day so it doesn't overrun your mailbox. Unsubscribe from mailing lists before you go out of town.

* Make sure your e-mail software is set to "Delete mail from server" once it downloads the messages. Otherwise, old mail will stack up on your ISP's server until the ISP starts bouncing incoming mail.

* Finally, if your ISP repeatedly bounces your mail, by all means sign up with a new provider.