Question: which protocol is used to send email messages from a mail client to a mail server
[{'answer': 'SMTP', 'provenance': [{'wikipedia_id': '27675', 'title': 'Simple Mail Transfer Protocol', 'start_paragraph_id': 1, 'start_character': 35, 'end_paragraph_id': 1, 'end_character': 39, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '27675', 'title': 'Simple Mail Transfer Protocol', 'start_paragraph_id': 14, 'start_character': 0, 'end_paragraph_id': 14, 'end_character': 767, 'bleu_score': 0.984904577301502, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 14269737028112030950}, 'section': 'Section::::Mail processing model.\n'}]}]