Handle user-mail-address being the empty string

* lisp/mail/feedmail.el (feedmail-fiddle-from):
* lisp/mail/rmail.el (rmail-unknown-mail-followup-to):
* lisp/mail/rmailsum.el (rmail-header-summary):
Belated update for 2002-09-29 startup.el change, 680ebfa, where
the value of user-mail-address during initialization was changed
from nil to the empty string.

3 files changed, 12 insertions, 9 deletions

diff --git a/lisp/mail/feedmail.el b/lisp/mail/feedmail.el
index 1402db40951..53791565bb1 100644
--- a/lisp/mail/feedmail.el
+++ b/lisp/mail/feedmail.el
@@ -2768,7 +2768,8 @@ return that value."
    ((eq t feedmail-from-line)
     (let ((feedmail-from-line
            (let ((at-stuff
-                  (if user-mail-address user-mail-address
+                  (if (> (length user-mail-address) 0)
+                      user-mail-address
                     (concat (user-login-name) "@"
                             (or mail-host-address (system-name))))))
              (cond
diff --git a/lisp/mail/rmail.el b/lisp/mail/rmail.el
index aeaba5862fc..695638fa062 100644
--- a/lisp/mail/rmail.el
+++ b/lisp/mail/rmail.el
@@ -2666,10 +2666,11 @@ Ask the user whether to add that list name to `mail-mailing-lists'."
                                       (regexp-quote (user-login-name))
                                       "\\($\\|@\\)\\|"
                                       (regexp-quote
-                                       (or user-mail-address
-                                           (concat (user-login-name) "@"
-                                                   (or mail-host-address
-                                                       (system-name)))))
+                                       (if (> (length user-mail-address) 0)
+                                           user-mail-address
+                                         (concat (user-login-name) "@"
+                                                 (or mail-host-address
+                                                     (system-name)))))
                                       "\\>\\)"))
                           addr))
                         (y-or-n-p
diff --git a/lisp/mail/rmailsum.el b/lisp/mail/rmailsum.el
index 7c7c9f48e70..729538173a0 100644
--- a/lisp/mail/rmailsum.el
+++ b/lisp/mail/rmailsum.el
@@ -757,10 +757,11 @@ the message being processed."
                                      ;; Don't lose if run from init file
                                      ;; where user-mail-address is not
                                      ;; set yet.
-                                     (or user-mail-address
-                                         (concat (user-login-name) "@"
-                                                 (or mail-host-address
-                                                     (system-name)))))
+                                     (if (> (length user-mail-address) 0)
+                                         user-mail-address
+                                       (concat (user-login-name) "@"
+                                               (or mail-host-address
+                                                   (system-name)))))
                                     "\\>\\)"))
                         from))
                    ;; No From field, or it's this user.