Now's as good a time as any to say what guidelines are used when discarding or blocking contributions to the tz mailing list. The tz mailing list discusses proposals for updates that would improve the time zone code and data. When contributions to the mailing list, on balance, harm the project more than help it, it is often advisable to discard them. Examples of abuse include (but are not limited to) spamming, commercial advertising, personal attacks, repetitive or out-of-scope topics, disinformation, sock puppetry, block evasion, copyright violations, and legal threats. An abusive mailing list correspondent should be blocked, with contributions discarded. The length of the block should depend on the severity of the offenses and the estimated future likelihood that future contributions would help more than harm. Correspondents whose contributions consist entirely of spam, for example, should be blocked permanently right away. Correspondents who make significant useful contributions should be treated more leniently: their first block should be for a period of a day to a week; the second, a month to six months; and later blocks, one year to permanent.