In order to route SSH (port 22) traffic via MWG, you can make use of SOCKS proxy in MWG.
In order to route SMTP traffic on port 25 you will need to make use of SOCKS proxy on MWG. With SOCKS proxy you can tunnel SMTP traffic via MWG.
The only way to pass SMTP on MWG is to use SOCKS Proxy.(version >7.4.2)(configure new port for this if you want, per default 1080). With version >= 7.4.2 you will find a "SOCKS Proxy" ruleset in the library.
By default SOCKS proxy port is 1080.
Just enable the port under Configuration>Proxies and create a policy for SOCKS traffic by using Common Rules > SOCKS Proxy from the Rule Library.
You can enable SOCKS proxy by navigating to configuration->Appliance->Proxies->SOCKS Proxy->Enable it.
Then in Policy tab you need to import SOCKS proxy rule set from library.SOCKS proxy rule set is present under Common rules.
Please refer below link to know more about SOCKS proxy:-