Our host does not support TXT records. (Waits for laughter to die down.) Yes, I know.
Is there an alternate way of setting up domainkey and SPF verification, like a custom MX and/or CNAME record?
If not, can I send CM campaigns from a subdomain, like firstname.lastname@example.org?
Unfortunately no, if your host does not support them, your options are either to send without authentication, or move your DNS hosting to a service which does support them, like DNSMadeEasy.
There is not an alternate way to set these things up, there is specifications which require the TXT records.
Is it a case of the host refusing to add TXT records, or that the DNS system they provide to you doesn't? As if it's the latter, try contacting them - you may find they'll be perfectly happy to insert the records manually themselves.
Thanks to you both.
@Stormy, no, the host I inherited can't do it manually. Needless to say, we will not be there much longer.
@Matthew, what about my subdomain idea, which can be hosted (and whose DNS can therefore be manipulated) elsewhere? E.g., list.example.com.
Also, does CM provide a hosted solution for subdomains?
No, I'm afraid we don't provide that kind of solution, it's really just the options I gave above.