One reason groups.io is flagged as spam more often than Yahoo! is Yahoo! is better known. Anti-spam tools use rules of thumb for picking out spam. One common rule is to flag mail from unfamiliar domains. Domains that don¡¯t have the older com-net-org-gov-mil-edu suffixes often get extra scrutiny. Since groups.io is less familiar, it gets flagged as spam more often. This growing pain may get better over time.
Both members checked their SPAM folders and, yes, all of the messages from our group were going in there.? I know it sound conspiratorial, but maybe Yahoo doesn't like the fact that I switched my group from Yahoo Groups to Groups.io.? Only the two members using Yahoo Mail were having the problem.? At any rate, it's fixed now.? Thanks for all your help.