svdr: > What can I do to find the reason for the timeouts? You need to find out where in the SMTP protocol the timeout happens.
- TCP connection setup. - SMTP Server '220' initial response. - EHLO, MAIL FROM, RCPT TO, DATA, end-of-data. Ideally, the PHP client would provide that information. Postfix logging will show 'lost connection after XXX', but that happens only for a completed TCP connection. Wietse