What is the standard port number for the unencrypted IMAP service? 06/14/2017 – by Mod_GuideK 0 What is the standard port number for the unencrypted IMAP service? A. 25 B. 143 C. 443 D. 993 E. 1066 SHOW ANSWERSCorrect Answer: B Explanation/Reference: Download Printable PDF. VALID exam to help you PASS.