Is there any support for sending/receive emails by multiple IP? For example to setup IP for domain, so it will be used to send and receive emails? I do not see such options inside ISPC, but maybe i didn't check something.
No, nothing specific for that at this time. Receiving emails is simple, you just create MX records for hosts which resolve to the ip address you wish mail to be delivered on, there's nothing special needed here. For outgoing mail you can set it up manually, the key setting is sender_dependent_default_transport_maps; you can search for a bit more info, but https://www.howtoforge.com/community/threads/different-ip-for-email.70582/ should get you going.
Ough. Too bad, i was hoping i can do everything inside ISPC (i'm avoiding changine files by myself, because there are problems when ISPC is updated - i may use the templates but they can be updated too, so it's too much work - especially when i use ISPC for automatizing things and not make them harder). Do You think it is a lot of work to implement it into ISPC?
That is very subjective. For someone familiar with ISPConfig coding already it wouldn't be a huge project with a minimal set of requirements. Eg. it's easy to see how to utilize the existing "Server ip addresses" to add a checkbox to mark addrs used for secondary mail addrs, then add a setting or Tab under Email > Domains > {domain} to select an ip address and set a hostname for smtp banner/helo hostname, and the postfix/dovecot config is not difficult to generate. But then you'll probably want to set up ssl certificates automatically for those addrs, and run into a showstopper in that ISPConfig currently has no way to issue certificates (I'm thinking letsencrypt here) on mail servers, only on web servers. If that's the case, then properly implementing what you want requires a future version of ISPConfig as a starting point, or to properly implement that at the same time, which gets into a lot more work.
