[IMail Forum] SMTP AUTH PROBLEM

[[EMAIL PROTECTED]/fabiopolo]

First sorry for my bad english.... In 2 last day we a have a lot of problem with our customer that use Outlook Express to send email by our SMTP server (5.09). We have NO MAIL RELAY, REFUSE NULL <> SENDERS and CHECK VALID SENDER enabled; DISABLE SMTP VRFY and DISABLE SMTP AUTH disabled. Our customer have enabled authertification in their Outlook Express. But 2 days ago someone of our customer have problems: the authetification  with a correct username and password be rejected. If  I stop an restart SMTP service for a few times the problem seem resolve... but in few hour the problem reappear. What is the cause? In which manner I can resolve? Thanks for help.