Xpath
/control/message/send-date
Immediately
<send-date>
<immediately></immediately>
</send-date>
15 mins after the campaign is loaded into Mapp Engage
<send-date>
<in>PT15M</in>
</send-date>
A specific date and time format relative to GMT
<send-date>
<date>2020-11-12T18:00:00+02:00</date>
</send-date>
A specific date and time format relative to GMT. With a delay parameter
<send-date>
<date max-delay-minutes="90">2018-06-30T18:00:00+02:00</date>
</send-date>
For a date in the past
<error>Entity has invalid fields: control/message/send-date=Tue Nov 12 22:00:00 CET 2019
(illegal_value): must not be more than ... minutes in the past.. </error>