For any mission critical applications where email is required, I've still been using a plugin for this functionality. I prefer 360works email plugin, but smtpitpro is another popular option.
Plugins will give you more robust control over the headers that are generated when you send mail, as well as hosts of other useful features.
Sounds like an update by your mail provider could have broken your headers. The only other cause would be a system time issue on your server or client that's sending the filemaker emails.
Can you try sending mail manually (via system client instead of SMTP) to see if you still have issues? That would at least narrow it down a little.
I am getting the same 4 hours before timestamp in the notification emails, scheduled or defined in the Console using FMS13v02. The emails are being sent at the correct time. I have tried with a diffferent email account from another provider and the same happens, so the problem is with FileMaker.
It looks like a bug to me
Is the time difference at your ISP (email hosting provider) perhaps? (just stabbing at the ether here... )
Pedro, also please post a new thread instead of resurrecting a thread from a year ago. A LOT has changed in filemaker in a year.