A bit of background info, first:
I have a domain that is configured to run a mail server, iRedadmin, postfix, etc. I can receive and send email and everything works great. The problem lies in the fact that after I decided to sign up for an online portfolio hosting service, they wanted me to change my domain's A @ entry in the DNS to point to their server IP, so that I could use my own "custom domain" instead of their generic subdomains, so that instead of going to sub.domain.com/portfolio, I could go to my-domain.com/portfolio to visit my site, which is in fact hosted on their servers.
After changing my A @ entry to point to their IP, everything worked fine, I could send email but not receive any. The problem lied in the fact that when someone tried sending email to, say, email@example.com, all the mail was really directed to their IP rather than my one, so in theory, they should have received all my mail.
I have solved the problem by creating a subdomain that points to my domain, e.g. webmail.domain.com and creating an MX entry that points to webmail.domain.com. Email works fine, however, now I have problems with ssh connection. I can connect to my domain by using its IP address, but if I use the domain, it actually connects to the portfolio hosting service's IP. Sad face.
My question: is it possible to create a DNS entry that applies only to certain ports? So I could ssh/FTP through port 22/21,etc... and use my local IP instead of theirs?
Thanks for helping, this is really important!