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Sending Blind Carbon Copies of Email
Anonymous FTP
Sending Blind Carbon Copies of Email
The BCC (blind carbon copy) field of an email message contains the identity of recipients of the message in addition to those in the To and CC fields. The contents of this field are not included in messages sent to recipients in the To and CC fields. Some mail systems choose to include the text of the BCC field only in the author's copy of the mail, while others also include it in the text sent to all those indicated in the BCC list.
The Elm mail system on a Unix machine such as frogmouth does not include the text of the BCC field in the mail of people in the BCC list. This is a useful feature that can be exploited for sending documents to several people, while keeping their names and addresses confidential. For instance, a survey could be sent to many people whose names were all listed in the BCC field. Each person would receive a copy of the survey without knowing who else had been sent one. The only names they would know of would be those provided in the To and CC fields, if any.
Pegasus mail, on the other hand, does include a copy of the BCC text in all mail sent to people in the BCC list. This means that people in the To and CC fields do not know that blind carbon copies have been sent, but everyone in the BCC field is aware of all the recipients.
Anonymous FTP is a means by which archive sites provide general access to their archives of information. These sites provide a special account called 'anonymous' or 'ftp'. User 'ftp' has limited access to the archive host, as well as some operating restrictions. In fact, the only operations allowed are logging in using FTP, listing the contents of a limited set of directories, and retrieving files. Some sites limit the contents of a directory listing an anonymous user can see as well.
Traditionally, this anonymous user account accepts any string as password, although it is common to use the password guest or one's email address. Some sites now explicitly ask for the user's email address and will not allow access using the password 'guest'. Providing an email address is a courtesy that allows archive site operators to get some idea of who is using their services.
Sample anonymous FTP commands are given below using the machine frogmouth. Although frogmouth requests that the user provide an email address as password, access is still provided when any string is given. This session obtains the text file file1.txt and the binary file file2 from directory pub; then changes to directory incoming and puts text file myfile.txt:
ftp frogmouth.bhs.mq.edu.au
cd pub
get file1.txt
bin
get file2
cd ../incoming
put myfile.txt
quit
Files can be downloaded by anonymous FTP from any directory on frogmouth to which user 'ftp' has access. Files may only be uploaded to the incoming directory. When a file is put in the incoming directory, it is owned by user 'ftp'. Thus there is no way of determining who the original owner of a file was, once it has been uploaded anonymously into the incoming directory. However, anyone who ftp's to frogmouth is able to download a copy of these files, for as long as they remain in this directory.
Much of this information has been taken from RFC (Request For Comments) and FYI (For Your Information) documents available by anonymous FTP from plaza.aarnet.edu.au.