diff --git a/doc/misc/gnus.texi b/doc/misc/gnus.texi
index 2c80231f18a..34ecfb040ec 100644
--- a/doc/misc/gnus.texi
+++ b/doc/misc/gnus.texi
@@ -15357,7 +15357,7 @@ symbols in @code{imap-stream-alist}.  Right now, this means
 Which authenticator to use for authenticating to the server, this is
 one of the symbols in @code{imap-authenticator-alist}.  Right now,
 this means @samp{gssapi}, @samp{kerberos4}, @samp{digest-md5},
-@samp{cram-md5}, @samp{anonymous} or the default @samp{login}.
+@samp{cram-md5}, @samp{plain}, @samp{anonymous} or the default @samp{login}.
 
 @item :program
 When using the @samp{shell} :stream, the contents of this variable is
@@ -27096,14 +27096,15 @@ Gnus supports both encoding and decoding.
 @item S/MIME---RFC 2633
 RFC 2633 describes the @acronym{S/MIME} format.
 
-@item IMAP---RFC 1730/2060, RFC 2195, RFC 2086, RFC 2359, RFC 2595, RFC 1731
+@item IMAP---RFC 1730/2060, RFC 2195/4616, RFC 2086, RFC 2359, RFC 2595, RFC 1731
 RFC 1730 is @acronym{IMAP} version 4, updated somewhat by RFC 2060
 (@acronym{IMAP} 4 revision 1).  RFC 2195 describes CRAM-MD5
 authentication for @acronym{IMAP}.  RFC 2086 describes access control
 lists (ACLs) for @acronym{IMAP}.  RFC 2359 describes a @acronym{IMAP}
 protocol enhancement.  RFC 2595 describes the proper @acronym{TLS}
 integration (STARTTLS) with @acronym{IMAP}.  RFC 1731 describes the
-GSSAPI/Kerberos4 mechanisms for @acronym{IMAP}.
+GSSAPI/Kerberos4 mechanisms for @acronym{IMAP}.  RFC 4616 describes
+AUTH=PLAIN authentication for @acronym{IMAP}.
 
 @end table
 
diff --git a/etc/NEWS b/etc/NEWS
index 7b2d2626d8d..b790c7e318c 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -1336,6 +1336,14 @@ This contains the list of regular expressions used to match "Re:" and
 international variants of it when modifying the Subject field in
 replies.
 
+** Imap
+
+---
+*** 'imap-authenticate' can now use PLAIN authentication.
+"AUTH=PLAIN" support is auto-enabled if the IMAP server supports it.  Pass
+a specific authentication type to 'imap-authenticate' or remove 'plain'
+from 'imap-authenticators' if you do not wish to use "AUTH=PLAIN".
+
 ** Rmail
 
 +++
diff --git a/lisp/net/imap.el b/lisp/net/imap.el
index 17f54e8d519..f705da317e5 100644
--- a/lisp/net/imap.el
+++ b/lisp/net/imap.el
@@ -275,6 +275,7 @@ stream.")
 			      digest-md5
 			      cram-md5
 			      ;;sasl
+                              plain
 			      login
 			      anonymous)
   "Priority of authenticators to consider when authenticating to server.")
@@ -284,6 +285,7 @@ stream.")
     (kerberos4  imap-kerberos4-auth-p imap-kerberos4-auth)
     (sasl	imap-sasl-auth-p      imap-sasl-auth)
     (cram-md5   imap-cram-md5-p       imap-cram-md5-auth)
+    (plain      imap-plain-p          imap-plain-auth)
     (login      imap-login-p          imap-login-auth)
     (anonymous  imap-anonymous-p      imap-anonymous-auth)
     (digest-md5 imap-digest-md5-p     imap-digest-md5-auth))
@@ -853,6 +855,23 @@ t if it successfully authenticates, nil otherwise."
 						(imap-quote-specials passwd)
 						"\""))))))
 
+(defun imap-plain-p (buffer)
+  (imap-capability 'AUTH=PLAIN buffer))
+
+(defun imap-plain-auth (buffer)
+  "Login to server using the AUTH=PLAIN command."
+  (message "imap: PLAIN authentication...")
+  (imap-interactive-login
+   buffer
+   (lambda (user passwd)
+     (imap-ok-p
+      (imap-send-command-wait
+       (concat "AUTHENTICATE PLAIN "
+               (base64-encode-string
+                (format "\000%s\000%s"
+                        (imap-quote-specials user)
+                        (imap-quote-specials passwd)))))))))
+
 (defun imap-anonymous-p (_buffer)
   t)