Bug#828801: Legitimate mail can contain long lines

[Andreas Metzler]

Control: tags -1 pending

exim4 (4.88~RC6-2) UNRELEASED; urgency=medium
 .
   * Add macro MAX_PHYSICAL_LINE_LENGTH with a default value of 998 to allow
     overriding the SMTP physical line length limit both for SMTP DATA ACL and
     remote_smtp* transports. Closes: #828801
     Also update corresponding NEWS entry.