Others sit at the end of 2400-baud modem connections that they pay for by the minute. If you have a high-bandwidth connection, be considerate of those who don't. You can economize by reading and composing messages offline. Most of the newer, more powerful mail programs, including those that are web-based, allow the option of sending messages in html format. Do not choose this option.
Many readers can only view plain text.
Likewise, ease of retrieving attachments is determined by the capabilities of the software. For some, the challenge is overwhelming. Do not send attachments to the entire group. If you have a document that may be of general interest, make the offer to the group, and wait for individual responses. Phone and fax numbers, additional e-mail and internet addresses, including home pages are usually listed to offer alternate means of contact.