I'd venture a guess at the software still being misconfigured in some fashion. I doubt they filter SMTP for encapsulated traffic, which is IPv6 in nature.
HINT - if you can't connect locally, it isn't your ISP

Also, you have 4 different IPv6 addresses in some sort of attempt at round-robin dns for your MX, one of which is a link-local which totally isn't going to be reachable for the global internet:
;; QUESTION SECTION:
;ramon-romero.com. IN MX
;; ANSWER SECTION:
ramon-romero.com. 3600 IN MX 0 ramon-romero.com.
;; ADDITIONAL SECTION:
ramon-romero.com. 3600 IN AAAA 2002:bd86:1a4e::bd86:1a4e
ramon-romero.com. 3600 IN AAAA 2002:c999:5f33::c999:5f33
ramon-romero.com. 3600 IN AAAA 2002:c058:6301::c058:6301
ramon-romero.com. 3600 IN AAAA fe80::7cfa:cd25:ce7:5d31
ramon-romero.com. 3600 IN A 201.153.95.51