From Longman Dictionary of Contemporary Englishsend something/somebody ↔ in phrasal verb1 TCMSENDto send something, usually by post, to a place where it can be dealt with I sent in a few job applications last week.2 SENDto send soldiers, police etc somewhere to deal with a difficult or dangerous situation British troops were sent in as part of the peace-keeping force. → send→ See Verb table
Examples from the Corpus
send in• If anyone has a quiz for a future issue - please send it in.• The first group was sent home in a widely criticised night operation two weeks ago.• The first quarterly accounts with the new rates will be sent out in July.• They were sent to him in packages of ten cartons from Moscow.• He was sent to work in the fields.• These women should never have been sent to prison in the first place.• The best IBMers were sent out in the seventies on secondments, then seen to come back into promotions.From Longman Business Dictionarysend in phrasal verb [transitive]1 send something → in to send something, usually by mail, to a place where it can be dealt withCustomers can send in their sales receipts to get the discount coupons.2 send somebody → in to tell someone to go somewhere to do a particular task, especially a difficult oneThe DTI may send in inspectors who will, if necessary, stop the company trading. → send→ See Verb table 