For nm.debian.org, at 2021-11-18:
Since april this year, I have worked with Julien Lamy on xsimd.
Prior to that, I also had discussion on mrtrix3 on -med mailing list.
Julien Lamy sent mails using the email address email@example.com
which is the one they're using on nm.debian.org.
I have made the following checks for their keys:
1. Checked a few mails for signatures - both on mailing list, and in private mail exchanges
and that indeed matches their keys
2. Checked their signed commits to the repositories they committed recently to
3. Made sure that they are able to decrypt the messages sent to them with their GPG key.
Due to my past interactions with Julien, I'm convinced that Julien Lamy as they
present themselves on nm.debian.org is the rightful owner of both email
firstname.lastname@example.org and GPG key 8BDD 0130 80E9 A0E8 C0D6 A157 3B36 5DE9 3EBD 1CD4.