From Longman Business Dictionary
mailingmail·ing /ˈmeɪlɪŋ/ noun [countableC]MARKETING an occasion when information or advertising material is sent through the mail to a large number of people at one time, or the information or advertising material sent in this waySYN BrE mailshotTick this box if you do not wish to receive mailings from other companies.
She follows up the mailings with phone calls.