Prepare envelope from

app/src/main/java/eu/faircode/email/EmailService.java

@@ -332,6 +332,10 @@ public class EmailService implements AutoCloseable {
         properties.put("mail." + protocol + ".ignorebodystructuresize", Boolean.toString(enabled));
     }
 
+    void setMailFrom(String address) {
+        properties.put("mail." + protocol + ".from", address);
+    }
+
     void setSendPartial(boolean enabled) {
         properties.put("mail." + protocol + ".sendpartial", Boolean.toString(enabled));
     }

app/src/main/java/eu/faircode/email/EntityIdentity.java

@@ -27,6 +27,7 @@ import androidx.annotation.NonNull;
 import androidx.room.ColumnInfo;
 import androidx.room.Entity;
 import androidx.room.ForeignKey;
+import androidx.room.Ignore;
 import androidx.room.Index;
 import androidx.room.PrimaryKey;
 
@@ -62,6 +63,8 @@ public class EntityIdentity {
     public String name;
     @NonNull
     public String email;
+    @Ignore
+    public String envelopeFrom;
     @NonNull
     public Long account;
     public String display;

app/src/main/java/eu/faircode/email/ServiceSend.java

@@ -793,6 +793,8 @@ public class ServiceSend extends ServiceBase implements SharedPreferences.OnShar
         } else {
             EmailService iservice = new EmailService(this, ident, EmailService.PURPOSE_USE, debug);
             try {
+                if (ident.envelopeFrom != null)
+                    iservice.setMailFrom(ident.envelopeFrom);
                 if (send_partial)
                     iservice.setSendPartial(true);
                 iservice.setUseIp(ident.use_ip, ident.ehlo);