The multi-part e-mail bitbucket sends for commits has a text part, which looks like this:

XY has pushed commits to user/repo.

You can view commits for this repository at the following link:

https://bitbucket.org/user/repo/commits/

Commits:

https://bitbucket.org/user/repo/commits//hash

...

You can see that the commit link below Commits: has a double slash before the commit hash, which makes the link broken. This is fine in the html part of the mail.