You can white list this email in Yahoo and/or if you use custom domain you can create an SPF record for your domain to specify that Wild Apricot
servers are allowed to send emails on your behalf. Read more about
Sender Policy Framework 
or
About SPF on WikiPedia 
.
Otherwise there is a chance that some spam blockers will filter our
emails sent from Wild Apricot on your behalf. If your domain does not
yet have an SPF record, DNS should be modified to include a TXT-record
like this:
"v=spf1 mx include:memberlodge.org ~all"
If you already have an SPF record, add this:
include:memberlodge.org before the word 'all'
Denys Zlobin
Helpful Apricot
http://www.wildapricot.com