Editors appreciate a brief note if it is a multiple submission, but it's not required. Creators who have talent and experience in a variety of print forms are attractive to syndicates. A syndicated column and a book can enhance each other. Some syndicates seek newsletters that can add another dimension to material that can't appear in the column. The lecture circuit is a good place to gather column material and mention your column.
Many newspapers offer news and information via their own online service or commercial services.
TMS and its creators provide news and entertainment to many online services and Web sites. And e-mail is often a popular way to involve newspaper readers in your comic or column. You'll likely receive spontaneous feedback, positive and negative, via e-mail. Generally, you should not call to confirm arrival of your submission. Most syndicates will give you some idea how long the review process normally takes.