This service is probably not very useful for manual use, however it has pretty good API (without any limits)!
It has two major endpoints:
http://mail.re146.dev/api/list/<md5 of inbox> to get list of received messages Example: http://mail.re146.dev/api/list/ad977c83bc0ddb1763bfc986092a070b for test@re146.dev
and
http://mail.re146.dev/storage/<md5 of inbox>/<message ID received from /api/list query> to get the received message Example: http://mail.re146.dev/storage/ad977c83bc0ddb1763bfc986092a070b/9b2854238441fc5cbfa0700f2251cfe7 for test@re146.dev and message with ID of 9b2854238441fc5cbfa0700f2251cfe7
All messages are stored for around 10 minutes. There are no limits at all of using the API.