I have an off-site user, with Outlook 2007 who is unable to send via SMTP. She is attempting to use the account from her ISP (no port 25 blocking issue). The ISP (clearwire) uses Gmail for both PO3 and SMTP service. There is one very odd aspect to this issue, if we run a test in the account settings dialog, it completes just fine (although the test message never seems makes it through). No issues with incoming (POP). We've attempted to use no encryption (port 25), SSL (port 465) and TSL (587) to no avail. We've contacted the ISP and they say it's our issue. When we change the encryption, we have seen errors that say that the method is not allowed - although both clearwire and gmail say to use SSL. On a side note, this happened after the user was away for about a week, she did set up a rule to be used as an auto-reply, but we have since removed the rule.
Any suggestions would be highly appreciated.