Temp Mail APIA small inbox.
A simple API.

# Requires curl and jq. Keep the jar private.
umask 077
JAR=$(mktemp)
API="https://inboxflick.com/v1"

# Create an inbox and save its possession cookie
MAILBOX=$(curl --fail-with-body -sS -c "$JAR" \
  -H 'Content-Type: application/json' \
  -d '{}' "$API/mailboxes")
ID=$(printf '%s' "$MAILBOX" | jq -er '.data.mailbox.id')
printf '%s\n' "$MAILBOX" | jq '.data.mailbox'

# Select it, preserving both cookies
curl --fail-with-body -sS -b "$JAR" -c "$JAR" \
  -X POST "$API/mailboxes/$ID/select"

# Send a test email from your own mail provider,
# then read the inbox (poll every 5 seconds or slower)
curl --fail-with-body -sS -b "$JAR" "$API/messages"

# When finished: destroy the inbox, then remove the jar
# curl --fail-with-body -sS -b "$JAR" -c "$JAR" \
#   -X DELETE "$API/mailboxes/current"
# rm -f "$JAR"