To cite package ‘mailmerge’ in publications use:

  de Vries A (2024). _mailmerge: Mail Merge Using R Markdown Documents
  and 'gmailr'_. R package version 0.2.5, ,
  <https://github.com/andrie/mailmerge>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {mailmerge: Mail Merge Using R Markdown Documents and 'gmailr'},
    author = {Andrie {de Vries}},
    year = {2024},
    note = {R package version 0.2.5, 
},
    url = {https://github.com/andrie/mailmerge},
  }