Yes, you can use Proton Mail on a cover letter if the address looks professional and you check it consistently. Here is when it helps, where it can raise questions, and how to use it well.
Yahoo Mail can work on a cover letter if the address looks professional, stays organized, and is an inbox you reliably monitor during your job search.
Outlook is usually fine on a cover letter if the address looks professional, belongs to you, and is an inbox you monitor consistently during your job search.
Gmail is usually fine on a cover letter if the address looks professional, matches your application materials, and is an inbox you actively monitor.
Usually no. Most cover letters should list one reliable phone number, but there are a few cases where a clearly labeled second number can help without confusing employers.
Usually no. A temporary email is a poor fit for LinkedIn because the account, recruiter replies, and recovery flow may need to last for years. Learn the privacy upside, the biggest continuity risks, and better alternatives.
Usually no. A cover letter works best with one clear reply address. Here is when two emails create confusion, when an exception makes sense, and what to do instead.
Should you list two phone numbers on LinkedIn? Learn when it helps, when it creates confusion, and how to stay reachable without exposing more personal data than you need to.
Usually no. One clear professional email is better than two on LinkedIn because it reduces confusion, limits spam exposure, and keeps recruiter follow-up simple.