Adding support for DMARC/SPF in outgoing mail configuration

In order to use DMARC, SPF is needed. However, there is a limit to how complicated a single SPF record can be made, in which only a limited number of DNS requests can be utilized to resolve the record. In other words, a very complex SPF record may not be resolved completely.

The solution to this limitation is to use different return-paths to different functions. With that said, in order to optimize an SPF record, additional configurations for return-paths are needed in JIRA outgoing mail configuration.