Long URL links in E-Mail Messages

We have a VB application that creates e-mail messages containing a URL that points to UPS and has tracking number information. The URL is long and we’ver noticed that some browsers don’t seem to recognize that the URL continues on the next line. It looks like the e-mail message coming from our VB app has a right margin and only allows the message to be a certain width. We can find no place to specify a line length or number of characters. Has anyone seen this and can it be fixed?