The standard (free) service starts shortly after 1am US eastern time; the emails are usually sent within one to five hours. Emails are only sent if there is a relevant post from the prior day.   If there is a delay in a mailing it will usually be blogged about on the FeedBlitz News blog by 9:30 or so US eastern.

Standard (free) service publishers may change their time zone from their publication's syndication settings menu found at www.feedblitz.com/f?lists  The time zone affects two items: when the email update starts, and what postst are included in it.  Posts are included from midnight to midnight, local time (as determined by the time zone).  The time zone update runs at 1:30 am time zone local time.  The time zone setting is ignored for publishers with "Turbo" upgrades, as the Turbo settings determine when an update is sent.

For "Turbo" users, emails are sent depending on the "Turbo" frequency (hourly, every 4 hours, every 8 hours or every 12 hours). If there are no posts in the previous timeframe (1, 2, 4, 8 or 12 hours) then no post is sent.  For users of the weekly and monthly "Turbo" features, the timespan used is the prior week or the same day in the previous month.  Monthly and weekly updates go out shortly after midnight, US eastern time.

"On demand" is another option available when you upgrade to Turbo. It lets you manually control when to send an update out, and what to send.  When you start an on-demand mailing, it presents you with a list of posts in your feed.  Using check boxes, you can pick which articles to send, and then instruct Feedblitz to send the updates.

Finally, there is the "Express" version of Turbo. It delivers new articles automatically, within 15 minutes of your posting them.  If you have a ping service, Express responds to an "extended ping" for immediate mailouts.

All Turbo upgrade options are available from the Turbo settings page for each feed.  View your syndications, invoke the popup menu for the publication you want to change, and then pick the Customizie | Delivery Schedule (Turbo) option.  Express, On Demand and the other options are in the drop down.  The service has a free 2 week evaluation period for new subscribers.