Development approach or architecture for email support in online help desk

Development approach or architecture for email support in online help desk

Please do not remind me that there are already tons of online help desk
available and we can use one of them.
I have to create a SaaS/Online help desk. I would like to know how to
achieve email support part of it.
One of the requirements is Companies/Individuals who use this help desk
may want to keep their own existing email address for their customers to
send support requests.
There are two options to achieve above (as far as I understand)
Option 1: Either companies need to set an email forwarding rule to forward
emails e.g. support@company.com forwards to support@testhelpdesk.com.
CompanyCustomers sends email to company specific email -> [Company has set
forwarding rule]-> Email arrives at Our Help Desk and converted to a
support ticket.
Option 2: This help desk software allows adding settings for IMAP/Pop
polling e.g. we ourselves poll companies email provider servers to grab
emails for a specific email account.
CompanyCustomers sends email to company specific email -> Our Help Desk is
polling that IMAP email account after every few seconds and
parsing/converting emails to support tickets.
We have to limit the help desk to allow only 1 of the above options in the
phase 1 development.
We kind of like option 1 but
There might be 100 or more companies using the helpdesk and choose to keep
using their own support email address for their customers and forwards
emails to our helpdesk.
Question for option 1: Is is possible/good idea that all companies forward
emails to our one email address and then we parse email to know which
email belongs to which company?
e.g. company1Customer -> emails to company1@company1.com ->
company1@company1.com has forwarded rule set to ->
support@testhelpdesk.com
company2Customer -> emails to company2@company2.com ->
company2@company2.com has forwarded rule set to ->
support@testhelpdesk.com
Is it even possible to know which email address an email has been
forwarded from?
Do we must create one unique email address per company so they set
forwarding rule to this unique email?
Questions for option 2: Is that solution good?