Email over SSB - sailmail. costs a few bucks a year. equipment costs $$
Email over HAM frequences - winlink. free, but ham license is a few bucks. equipment costs $$
Email over Satellite - $$$$ service and equipment
Really depends where you are cruising. Wireless Internet is available throughout the USA. In the Bahamas it is available in a lot of areas through Betelco and most marinas have free wifi. Out at sea it's not so convenient and then you are into SSB or satellite. Satellite has come way down in price and is a cheaper option than SSB.
To send and receive email via SSB you also need Pactor
True as far as it goes.
We can break e-mail and Internet communications down into three categories: very short range, short range, and long range.
Very short range is dominated by WiFi. You can make WiFi more convenient with a range extender. The Ubiquity Bullet dominates the market here, although Alfa makes some decent products. Most of the best known marine WiFi range extenders from IslandTimePC, RogueWave, WiFiforSailors are repackaged Bullets. Cost is nominal for hardware and WiFi is readily available in most places for reasonable fees; sometimes local businesses make WiFi available for free - if you use such services it is polite to buy a beer from the restaurant whose connection you use, or otherwise support the business that supports you. Effective use of WiFi is generally limited to anchorages and marinas.
Short range is mostly cellular in nature. You can use many cell phones to connect to the Internet through the phone or use a MiFi device for a dedicated cellular connection to the Internet. For ICW cruisers you can generally get decent coverage from Norfolk to Key West. Depending on your service provider you may find some dead spots through North Carolina.
Long range is the province of e-mail over SSB and satphones. You can get some web service over satphones but it is such an expensive exercise in frustration that you should not count on it.
Hardware for e-mail over SSB is a bit more expensive than e-mail over satphones. Running costs for satphones are much much more than for SSB. The breakeven point is less than two years.
Don't get sucked in by handheld satphones and "portable" data kits. You will end up doubling your hardware costs with a car kit and external marine antenna to get decent performance.
You have options for e-mail over SSB. With a Pactor modem (about $1800US over the SSB) you can use commercial services like Sailmail, CruiseEmail, and Shipcom AND the Winlink ham service (General class license or above in the US). Winlink offers free software for an alternate protocol called WINMOR that only works on their network but does not require a Pactor modem. WINMOR service is still in its early days and coverage can be spotty depending on where you travel.
Note that to use Winlink or ham radio in particular outside the US you'll need a local reciprocal license. In some countries (including the Bahamas and BVI) you'll need a country specific license. In other places that the US has treaties with you reciprocity is automatic or nearly so. In some cases including much of Europe you need a US Extra Class license for reciprocity.
In my opinion, absent the regulatory information that is easy to learn, all the technical information required to pass a US General class ham license and most of what is in the Extra class license is necessary for a responsible self-sufficient cruiser anyway.