Issue #2223967 by jofitz, LKS90, AdamPS, sja112, shaktik, pminf, Berdir, mxr576, bmcclure, Manuel Garcia, naveenvalecha, Gogowitsch, andypost, alexpott, jonathanshaw, claudiu.cristea, greggles: Do not decode a contact message twice

Issue #2572801 by alexpott, vprocessor, andriyun, andypost, chishah92, Mile23, attiks, hussainweb, klausi, dawehner, pfrenssen: Fix 'Drupal.WhiteSpace.ScopeIndent' coding standard

Issue #2719695 by alexpott, Mile23: Fix 'Drupal.Classes.ClassDeclaration.CloseBraceAfterBody' coding standard

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #2358991 by JeroenT, ianthomas_uk, rpayanm, jamesdixon, er.pushpinderrana, Ashok Negi: Remove usage of drupal_mail()

Issue #2358995 by rpayanm, JeroenT, Alienpruts, gaurav.pahuja, er.pushpinderrana | Les Lim: Remove usage of drupal_wrap_mail().

Issue #950534 by mparker17, mgifford, Mixologic, jbloomfield, erinclerico, theMusician, wmostrey | zirvap: [policy] Consistently use email instead of e-mail in Drupal.

Issue #1889644 by Berdir: Convert drupal_mail_system() to a MailFactory service to allow more flexible replacements.

Issue #1471364 by amateescu: Move mail system classes from system.mail.inc to PSR-0 classes in Drupal\Core.