Let’s say at the suggestion of a trusted colleague you’ve reached out to someone he or she knows to request an informational interview.  Or perhaps you’ve reached out to someone you don’t know to see if they’re willing to give you some of their time to learn more about an industry, job, or related professional matters.

Congratulations! You’ve taken an important step towards gaining information and insight you’ll undoubtedly find valuable for your career. But what happens if, despite your effort, the person you’ve reached out to fails to respond to your inquiry? What should you do?  How hard should you try to connect with this person — and when does your persistence make you a pest? In other words, when does relentlessness become counterproductive and risk alienating individuals with whom you’d like to speak as part of your professional relationship building efforts?

There are no hard and fast rules regarding what’s appropriate in terms of attempting to connect with people. Undoubtedly, what one person considers as persistent exceeds the limits other people are willing to tolerate. That said, here are some guidelines I’ve come to rely on over the years that have enabled me to connect successfully with many individuals.

Determine, to the extent you can, the best initial means of approaching the individual to set up a subsequent phone call or in-person meeting.  While LinkedIn is a great way to find and reach out to people, I’ve learned that many individuals simply don’t check their LinkedIn mailboxes regularly.

I recommend two approaches for tackling this problem.  First, check an individual’s LinkedIn profile to see if there’s been recent activity (in terms of adding contacts, giving endorsements, writing recommendations, and/or updating their profile).  In my experience, such activity increases the likelihood that they checking their LinkedIn inbox regularly–but even then there’s still no guarantee.  You might send an InMail (a direct message to someone on LinkedIn) knowing that you’ll be notified if you do not receive a response (assuming you have a paid LinkedIn account).  Better still, I suggest a phone call or email to increase your chances of reaching the person directly. Whether that person responds or not is a whole other matter, of course.

Say you’ve reached out by phone or email and the individual does not respond.  I recommend following up once, twice at most, on your initial inquiry as people often overlook messages and appreciate a friendly reminder. I’d wait at least a week between each missive to allow the individual to have time to respond.  You also could alternate between phone and email in your efforts should your initial outreach not elicit a response, assuming you have at your disposal both means of contacting the individual.

I typically cease my outreach after two unsuccessful attempts to reach someone.  In my experience, any further effort risks being seen as overly aggressive. Yet situational variables have in some instances led me to break this rule.  These have included encouragement by either the individual who referred me in the first place or the person I’m trying to reach (who might advise me to try to connect repeatedly until the timing is right for a conversation).

I also consider alternatives, as there might be another person at the same organization or a related one who might be able to offer me comparable perspective or insight.

The bottom line is that connecting with people you don’t know is as much an art as it is a science.  Regardless of the approach you take, remember that your goal is to make a positive impression that contributes to a good reputation in the professional communities you aspire to inhabit.