display mail in iframe, add design for thread and unseen

back/db/structureV2.sql

@@ -67,7 +67,7 @@ CREATE TABLE bodypart (
   bodypart_id   INT AUTO_INCREMENT,
   bytes         INT NOT NULL,
   hash          TEXT NOT NULL,
-  text          TEXT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci,
+  text          TEXT,
   data          BINARY,
   PRIMARY KEY (bodypart_id)
 );
@@ -75,10 +75,10 @@ CREATE TABLE bodypart (
 -- 7
 CREATE TABLE source (
   message_id    INT NOT NULL,
-  content       BLOB NOT NULL,
+  content       TEXT NOT NULL,
   PRIMARY KEY (message_id),
   FOREIGN KEY (message_id) REFERENCES message(message_id) ON DELETE CASCADE
-)
+);
 
 -- 8
 CREATE TABLE field_name (
@@ -94,7 +94,7 @@ CREATE TABLE header_field (
   field_id        INT NOT NULL,
   bodypart_id     INT,
   part            VARCHAR(128),
-  value           TEXT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci,
+  value           TEXT,
   UNIQUE KEY (message_id, field_id, bodypart_id),
   UNIQUE KEY (message_id, field_id, part),
   FOREIGN KEY (message_id) REFERENCES message(message_id) ON DELETE CASCADE,