Dear Colleagues, Twenty years ago this month I initiated a mailing list on category theory. During the last two decades there have been many useful exchanges of ideas. Sometimes these have become heated. Eventually a policy on acceptable postings became necessary. That policy is on the web page for the list which is linked at the bottom of every message. It states: "The moderator will not modify articles except for minor typographical and formatting changes. Thus, no offensive or defamatory material should be sent (it will be returned and not posted), and inflammatory posts are discouraged. Nevertheless, wide latitude for vigorous debate is allowed. The categories mailing list distributes *only text* messages. *Do not send attachments, html or excessively long postings* (greater than about 10K). Postings with attachments or ones with html *will be discarded*; long postings may be. Help with avoiding html is here or here." No one has ever objected to the policy, and I have tried to follow it. The policy means that not everything sent to the list will be forwarded. That is the nature of a moderated mailing list. Recently several emails have been circulated to a long list of category theorists, and also sent to the categories list. Some of them have been rejected for forwarding because they do not comply with the policy above. This is regrettable. It is not a pleasure to reject items. I am writing to urge all members of the categories list to read the policy again and to ensure that any message sent to the list has been carefully considered and is acceptable. Using the "reply all" function has sometimes had unintended consequences. In particular, I would like to remind you all that messages containing html are *not* acceptable. Avoiding html is easy and a good idea anyway. Messages of more than a few paragraphs are also not suitable. The web provides many locations, some explicitly devoted to category theory, where longer items may be published. best wishes to all, Bob Rosebrugh [For admin and other information see: http://www.mta.ca/~cat-dist/ ]