Many would like to avoid spoofing and give certainty to their customers that the emails they are receiving are in fact from the merchant. As a standard setting in wallee, the From and ReplyTo email address is (firstname.lastname@example.org).
If you would like to work with a Sender Policy Framework (SPF) Record for your emails, in general this is not necessary if you are using wallee. All the emails that are sent out from wallee use the merchant's Email hoster if you set up the SMTP email. You are able to configure the From and the ReplyTo email addresses within wallee.
DomainKeys Identified Mail (DKIM) and Domain-based Message Authentication (DMARC) also become redundant if you are using wallee and have set everything up within your wallee space.
However, if you the merchant would like to use a third party SMTP, it is probably worth mentioning in the emails that the email coming from this address is in fact from that hoster and not the merchant.
You can use another provider without using SMTP credentials such as Amazon SES, Mailgun to name a few.