nnheader-max-head-length

nnheader-max-head-length is a variable defined in `nnheader.el'.
Its value is

8192

Documentation:
*Max length of the head of articles.

Value is an integer, nil, or t. nil means read in chunks of a file
indefinitely until a complete head is found; t means always read the
entire file immediately, disregarding `nnheader-head-chop-length'.

Integer values will in effect be rounded up to the nearest multiple of
`nnheader-head-chop-length'.