pip install mailsave==0.8.1

Dump emails to a file. It can be used as a remplacement for sendmail or an SMTP server.

Source
Among fairly niche packages on PyPI.
Over 550 downloads in the last 90 days.

Version usage of mailsave

Proportion of downloaded versions in the last 3 months (only versions over 1%).

0.8.1

18.00%

0.5.0

15.82%

0.8.0

15.64%

0.4.0

12.73%

0.1.0

12.73%

0.3.0

12.73%

0.2.0

12.36%