engine: Detect mime encoding constraint from server EHLO

Fix #1416

src/client/composer/composer-widget.vala

@@ -1723,7 +1723,7 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
             Geary.ComposedEmail draft = yield to_composed_email(null, true);
             yield this.draft_manager.update(
                 yield new Geary.RFC822.Message.from_composed_email(
-                    draft, null, null
+                    draft, null, GMime.EncodingConstraint.7BIT, null
                 ),
                 null,
                 null

src/client/plugin/mail-merge/mail-merge-folder.vala

@@ -326,7 +326,7 @@ public class MailMerge.Folder : Geary.AbstractLocalFolder {
                 var processor = new Processor(this.template);
                 var composed = processor.merge(fields);
                 var message = yield new Geary.RFC822.Message.from_composed_email(
-                    composed, null, cancellable
+                    composed, null, GMime.EncodingConstraint.7BIT, cancellable
                 );
 
                 var id = new EmailIdentifier(next_id++);

src/engine/rfc822/rfc822-message.vala

@@ -236,6 +236,7 @@ public class Geary.RFC822.Message : BaseObject, EmailHeaderSet {
 
     public async Message.from_composed_email(Geary.ComposedEmail email,
                                              string? message_id,
+                                             GMime.EncodingConstraint constraint,
                                              GLib.Cancellable? cancellable)
         throws Error {
         this.message = new GMime.Message(true);
@@ -338,6 +339,7 @@ public class Geary.RFC822.Message : BaseObject, EmailHeaderSet {
                     null,
                     "text/plain",
                     true,
+                    constraint,
                     cancellable
                 );
             } catch (GLib.Error err) {
@@ -438,6 +440,7 @@ public class Geary.RFC822.Message : BaseObject, EmailHeaderSet {
                     body_charset,
                     "text/html",
                     false,
+                    constraint,
                     cancellable
                 );
             } catch (GLib.Error err) {
@@ -1200,6 +1203,7 @@ public class Geary.RFC822.Message : BaseObject, EmailHeaderSet {
                                                string? charset,
                                                string content_type,
                                                bool is_flowed,
+                                               GMime.EncodingConstraint constraint,
                                                GLib.Cancellable? cancellable)
         throws GLib.Error {
         GMime.Stream content_stream = new GMime.StreamMem.with_buffer(content);
@@ -1211,7 +1215,7 @@ public class Geary.RFC822.Message : BaseObject, EmailHeaderSet {
 
         GMime.ContentEncoding encoding = yield Utils.get_best_encoding(
             filter_stream,
-            GMime.EncodingConstraint.7BIT,
+            constraint,
             cancellable
         );
 

src/engine/smtp/smtp-capabilities.vala

@@ -12,6 +12,7 @@ public class Geary.Smtp.Capabilities : Geary.GenericCapabilities {
     public const string AUTH_PLAIN = "plain";
     public const string AUTH_LOGIN = "login";
     public const string AUTH_OAUTH2 = "xoauth2";
+    public const string 8BITMIME = "8bitmime";
 
     public const string NAME_SEPARATOR = " ";
     public const string VALUE_SEPARATOR = " ";

src/engine/smtp/smtp-client-service.vala

@@ -120,6 +120,21 @@ public class Geary.Smtp.ClientService : Geary.ClientService {
         throws GLib.Error {
         debug("Saving composed email: %s", email_subject(composed));
 
+        // Detect server encoding constraint
+        GMime.EncodingConstraint constraint = GMime.EncodingConstraint.7BIT;
+        try {
+
+            ClientConnection smtp = new ClientConnection(this.remote);
+            yield smtp.connect_async(cancellable);
+            yield smtp.say_hello_async(cancellable);
+            if (smtp.capabilities.has_capability(Capabilities.8BITMIME)) {
+                constraint = GMime.EncodingConstraint.8BIT;
+            }
+            yield smtp.disconnect_async(cancellable);
+        } catch (Error err) {
+            // Oh well
+        }
+
         // XXX work out what our public IP address is somehow and use
         // that in preference to the originator's domain
         var from = composed.from;
@@ -128,7 +143,10 @@ public class Geary.Smtp.ClientService : Geary.ClientService {
             : this.account.primary_mailbox.domain;
         Geary.RFC822.Message rfc822 =
             yield new Geary.RFC822.Message.from_composed_email(
-                composed, GMime.utils_generate_message_id(domain), cancellable
+                composed,
+                GMime.utils_generate_message_id(domain),
+                constraint,
+                cancellable
             );
 
         EmailIdentifier id = yield this.outbox.create_email_async(

src/mailer/main.vala

@@ -44,7 +44,7 @@ async void main_async() throws Error {
             }
 
             msg = yield new Geary.RFC822.Message.from_composed_email(
-                composed_email, null, null
+                composed_email, null, GMime.EncodingConstraint.7BIT, null
             );
         }
 

test/engine/rfc822/rfc822-message-test.vala

@@ -446,6 +446,7 @@ This is the second line.
         return yield new Geary.RFC822.Message.from_composed_email(
             composed,
             GMime.utils_generate_message_id(composed.from.get(0).domain),
+            GMime.EncodingConstraint.7BIT,
             null
         );
     }

test/integration/smtp/client-session.vala

@@ -133,6 +133,7 @@ class Integration.Smtp.ClientSession : TestCase {
         return yield new Geary.RFC822.Message.from_composed_email(
             composed,
             GMime.utils_generate_message_id(from.domain),
+            GMime.EncodingConstraint.7BIT,
             null
         );
     }