Added check for long attachment file names

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

@@ -4881,6 +4881,10 @@ public class FragmentCompose extends FragmentBase {
                     Log.i(ex);
                 }
 
+            // https://www.rfc-editor.org/rfc/rfc2231
+            if (attachment.name != null && attachment.name.length() > 60)
+                db.attachment().setError(attachment.id, context.getString(R.string.title_attachment_filename));
+
         } catch (Throwable ex) {
             // Reset progress on failure
             Log.e(ex);

app/src/main/res/values/strings.xml

@@ -1661,6 +1661,7 @@
     <string name="title_attachment_keywords">attached,attachment,attachments,included</string>
     <string name="title_attachment_reminder">Did you intend to add an attachment?</string>
     <string name="title_attachment_warning">Potentially dangerous: %1$s</string>
+    <string name="title_attachment_filename">Some other email clients cannot handle file names longer than 60 characters</string>
     <string name="title_plain_reminder">All formatting will be lost</string>
     <string name="title_dsn_reminder">Hard bounces damage the email reputation of the original sender!</string>
     <string name="title_size_reminder">Message (%1$s) larger than server limit (%2$s)</string>