How to correct Invalid Protocol: null sending mail using javax.mail
jakarta-mail, java, nosuchproviderexception
Solution
you might try another way:
Properties props = new Properties();
props.setProperty("mail.transport.protocol", "smtp");
props.setProperty("mail.smtp.host", "out.alice.it");
props.setProperty("mail.smtp.auth", "true");
final PasswordAuthentication auth = new PasswordAuthentication(smtpUser, stmpPassword);
Session mailSession = Session.getDefaultInstance(props, new Authenticator() {
@Override
protected PasswordAuthentication getPasswordAuthentication() { return auth; }
});
MimeMessage message = ....;
// compose the message
Transport.send(message);
Problem
i'm trying to send mail in this way: ``` Properties props = new Properties(); props.setProperty("mail.transport.protocol", "smtp"); props.setProperty("mail.host", "out.alice.it"); props.setProperty("mail.user", "mymail@domain.it"); props.setProperty("mail.password", "*****"); Session mailSession = Session.getDefaultInstance(props, null); Transport transport = mailSession.getTransport(); MimeMessage message = new MimeMessage(mailSession); message.setFrom(new InternetAddress("Host", "Name")); ``` On the row `Transport transport...` i retrieve this error: ``` javax.mail.NoSuchProviderException: Invalid protocol: null at javax.mail.Session.getProvider(Session.java:440) at javax.mail.Session.getTransport(Session.java:659) at javax.mail.Session.getTransport(Session.java:640) at javax.mail.Session.getTransport(Session.java:626) at Mail.sendMail(Mail.java:151) ``` How can i resolve? Can someone help me? Thanks!! :) EDIT: If i create a main and launch that method to send mail, it works good! My problem borns after i read mail into mail folder: ``` Properties properties = System.getProperties(); properties.setProperty("mail.store.protocol", "imap"); Session session = Session.getDefaultInstance(properties, null); Store store = session.getStore("pop3"); store.connect("pop3.domain.it", "mail@domain.it", "****"); Folder inbox = store.getFolder("inbox"); FlagTerm ft = new FlagTerm(new Flags(Flags.Flag.SEEN), false); inbox.open(Folder.READ_ONLY); Message messages[] = inbox.search(ft); for(Message message:messages) { if(message.getFrom()[0].toString().equals("aMail")){ sendMail(message.getFrom()[0].toString());//Error! } } ``` I Thought the exception borns cause i've opened store to get inbox mail so i edit in this way: ``` ArrayList<String> reply = new ArrayList<String(); for(Message message:messages) { if(message.getFrom()[0].toString().equals("aMail")){ reply.add(message.getFrom()[0].toString()); } } store.close(); for(String mail : reply){ sendMail(mail); // ERROR AGAIN! } ``` very strange.... SOLVED IN THIS WAY: i modified this row ``` Session mailSession = Session.getDefaultInstance(props, null); ``` to ``` Session mailSession = Session.getInstance(props); ```