BlueMail supports adding an attachment from your photos or videos libraries, documents, PDFs and other types of attachments. BlueMail uses native applications to open a viewer that is suitable for the attachment on the receiving end point, based on the receiver preferences.
To add an attachment to your email, get into Compose mode (or Reply, Reply all, Forward and similar actions), then tap the attach (paperclip) icon directly on the Compose screen and select your file(s).
On Desktop, you can also use the drag and drop feature to drag your file(s) into the Compose window.