They don’t necessarily need access to a local SMTP server, it can be a public one, such as Google’s smtp.gmail.com. The problem with Google’s SMTP server is that is has been known to “blacklist” an e-mail account if it thinks that there is a robot behind it sending automated e-mails, but it might work if the number of times an e-mail is sent is infrequent. Also, the ISP that the client’s office is using may offer an SMTP server as well, but probably follows similar protocol of “blacklisting”.
Outside of those options, there are 3rd party SMTP options, but you’ll have to be careful and make sure that the SMTP server itself hasn’t been “blacklisted” by other e-mail services. Google Apps (http://www.google.com/a) has some options, but I’m not too familiar with all of the available 3rd party options, hopefully others will chime in. How often will Ignition be sending e-mails in these scenarios?