The “Mailed” tracking event is USPS’s confirmation that they have custody of the mailpiece. You can utilize this tracking event to monitor Lob’s SLA adherence and also provide auditable proof and time of mailing. Please note, this data is only available in Enterprise editions of Lob.
The “Mailed” tracking event appears at earliest two business days after sending your Lob API request. In some instances, it can take longer for this “Mailed” event to become visible, but when surfaced, it will accurately reflect the actual date of mail handoff to the USPS.
Please note that tracking events are not guaranteed by USPS, though we typically receive tracking events on over 99% of our mailings.