I've started messaging Software/IT Managers on LinkedIn when there is no contact number and would welcome any advice on my approach. "Hi (Name), I've seen that (company name) are currently recruiting for a number of IT related roles, I'm sure that you already have a PSL or that you have these roles covered and wouldn't actually benefit from additional help. However, if that's not the case, I would love to set up a call and run through how I can help you fill these positions with the best candidates. Speak soon. Sash"