From Longman Dictionary of Contemporary Englishdrop somebody a linedrop somebody a lineinformalWRITE to write a short letter or email to someone Drop me a line and let me know how you’re getting on. → line
Examples from the Corpus
drop somebody a line• If any walls appear to lean, check by going back to the nearest upper window and drop a plumb line down.• Then get cracking, drop me a line with your suggestions.• Do drop me a line, Mrs Surridge, or anyone else who's interested.• Other cities have dropped their line items without allowing departments to keep any of their savings.• Why don't you give me a call or drop me a line sometime?• What ever the reason is, Mr Heaps, please drop us a line to tell us about it.• So if there are any problems drop me a line.• What do you think? Drop me a line at the Washington Post Weekend section and share your thoughts.• Do spare time to drop me a line.• If he can not do so, perhaps he will drop me a line. 