Add a tweak to control the delay when sending mails using gmail or hotmail. Fixes #8064 (Email 5 Min. Added to Options)

resources/default_tweaks.py

@@ -315,3 +315,11 @@ locale_for_sorting =  ''
 # metadata  one book at a time. If True, then the fields are laid out using two
 # columns. If False, one column is used.
 metadata_single_use_2_cols_for_custom_fields = True
+
+# The number of seconds to wait before sending emails when using a
+# public email server like gmail or hotmail. Default is: 5 minutes
+# Setting it to lower may cause the server's SPAM controls to kick in,
+# making email sending fail. Changes will take effect only after a restart of
+# calibre.
+public_smtp_relay_delay = 301
+

src/calibre/gui2/email.py

@@ -22,6 +22,7 @@ from calibre.customize.ui import available_input_formats, available_output_forma
 from calibre.ebooks.metadata import authors_to_string
 from calibre.constants import preferred_encoding
 from calibre.gui2 import config, Dispatcher, warning_dialog
+from calibre.utils.config import tweaks
 
 class EmailJob(BaseJob): # {{{
 
@@ -83,7 +84,7 @@ class Emailer(Thread): # {{{
         rh = opts.relay_host
         if rh and (
             'gmail.com' in rh or 'live.com' in rh):
-            self.rate_limit = 301
+            self.rate_limit = tweaks['public_smtp_relay_delay']
 
     def stop(self):
         self._run = False