I have a forwarding set up from a DH-hosted mail address to a Gmail account -- mails gets there quickly. In the other direction I've also never had any delays or problems. It just works for me -- but then I've of course whitelisted my Gmail address in my DH webmail!
So it turns out that DH is doing extra filtering on Gmail addresses. Reasonable in my mind because they're doing it to protect us from spam and I get enough as it is already. Perhaps the whitelisting will help, but more likely the DH filtering happens even before the mail gets to "our" own mail servers so it's inevitable.
In most cases, I don't mind to wait an hour or so on spam filtering if it works, but a 19 hours delay is too much. Oh, the joys of spam...
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