Searching for Articles

M-s: Search through all subsequent (raw) articles for a regexp (gnus-summary-search-article-forward).
M-r: Search through all previous (raw) articles for a regexp (gnus-summary-search-article-backward).
M-S: Repeat the previous search forwards (gnus-summary-repeat-search-article-forward).
M-R: Repeat the previous search backwards (gnus-summary-repeat-search-article-backward).
&: This command will prompt you for a header, a regular expression to match on this field, and a command to be executed if the match is made (gnus-summary-execute-command). If the header is an empty string, the match is done on the entire article. If given a prefix, search backward instead.
For instance, & RET some.*string RET # will put the process mark on all articles that have heads or bodies that match ‘some.*string’.
M-&: Perform any operation on all articles that have been marked with the process mark (gnus-summary-universal-argument).