I am an undergraduate computer science student entering my 3rd year of college. I plan on using letters of recommendation to get an internship in the tech industry for next summer. It is likely that I will get one letter of recommendation (from my manager from this summer's tech internship at a large company) that will be non-confidential. This question is about a second letter of recommendation from a professor with whom I did undergraduate research.
Is it highly recommended that this second letter be confidential?
If I keep it confidential, I will have to ask recruiters at career fairs for their email address (if we use a dossier service like Interfolio). This would help open up a line of communication but I'm not sure if it's likely that recruiters would give me their email address. Even if they did, it would take some time to send this letter of recommendation via email through a service like Interfolio. And once they get the letter of recommendation, my application would be scattered with my resume as a hard copy and this letter on email.
Or is it fine if I keep it non confidential which would enable me to freely share the letter by uploading it on online applications or handing it to recruiters at career fairs along with my resume? Would removing confidentiality drastically reduce the credibility of the letter? Also, would you even suggest doing the latter: handing the letter along with my resume?
Thanks in advance!