<p>When I reply to an e-mail from an interviewer, should I use her first name or last name? (Eg. Erin or Ms. Wilson?) I don't know her age.</p>
<p>Use her title.</p>
<p>And by title, I assume you mean Ms. Last Name?</p>
<p>Yes, Ms. or Mr. Last name</p>
<p>Ooh… I just found out that she’s in her 20s. Should I still use Ms? (Sorry about being so nitpicky. I feel a bit awkward calling someone who’s somewhat around my age Ms.) :[ Thank you so much for replying!</p>
<p>i believe ms. is generic; you can use ms. for married or unmarried. (thats what my mom says anyway 
) go moms</p>
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<p>Don’t call her by her first name unless she specifically instructs you to do so. Her age doesn’t matter. She is speaking in an official capacity and as such she should be offered a degree of automatic formality and respect. Use “Ms. Lastname.”</p>
<p>Ah. Thank you for clearing that up.</p>
<p>If she is married, I would use Mrs. The proper address on the envelope of the thank-you note that you will send is:</p>
<p>“Ms. Firstname Lastname” if unmarried, and “Mrs. Firstnameofhusband Lastname” if married.</p>