The timestamp comes from OpenBSD's struct timeval, which defines the
number of seconds as a time_t (i64) and the number of micro-seconds as a
suseconds_t (long, hence i64 too). They are separated by a dot.
https://man.openbsd.org/gettimeofday.2
The latest OpenSMTPD draft added the timeout event, it therefore has
been added to the parser. As shown in the new sessions examples, the
timestamp format changed and the parameters are also optional.
