I wasn't sure where to put this topic.... but tips and techniques seemed closest to appropriate. Here is a page with an excellent article on the subject:
https://www.sailingtotem.com/2016/07/the-best-mail-services-for-cruisers.html (https://www.sailingtotem.com/2016/07/the-best-mail-services-for-cruisers.html)
Below are two charts, but the discussion of the ins and outs of getting mail while cruising and the differences in the services offered makes the full text well worth reading.
(https://i1.wp.com/www.sailingtotem.com/wp-content/uploads/2016/07/best-mail-services-1.png?w=561&ssl=1)
(https://i1.wp.com/www.sailingtotem.com/wp-content/uploads/2016/07/next-best-mail-services-1.png?w=612&ssl=1)