Dave Crocker, Murray S. Kucherawy. Indicating Email Handling States in Trace Fields. RFC, 6729:1-12, September 2012. [doi]
@article{rfc6729, title = {Indicating Email Handling States in Trace Fields}, author = {Dave Crocker and Murray S. Kucherawy}, year = {2012}, month = {September}, doi = {10.17487/RFC6729}, url = {https://doi.org/10.17487/RFC6729}, researchr = {https://researchr.org/publication/rfc6729}, cites = {0}, citedby = {0}, journal = {RFC}, volume = {6729}, pages = {1-12}, }