blacklisted by a single user or by a single email server? they are not all one system. each server will reject of filter what it chooses and for however long it is programmed to do that for. some servers do it based upon if the majority user reports the email as spam or if the email address being sent to is not existent or if it's receiving too many messages within a short period of time. ex: 20 messages to joe@exanple.com in 1 minute.
and then there are some servers who will never accept anything from certain domains. work in a strickt medical or government office? it's possible that anything from Hotmail or Gmail or your domain name containing a triggered term will be blocked.. noreply@ no-reply@ mailer@ newsletter@ bulk@ info@ hello@ donotreply@ ...etc it may be rejected because your email is too short or doesn't include the expected native language, or the phrases used in the email are confusing.
using an email address that isn't your domain, while delivering content on behalf of the forum domain also has a high chance of getting filtered out. ex: sending example@gmail.com email from forum@example.com domain.
it's also possible that an email server may be down at the time of your first mailing, but will be back up and running be the time you send out something to them next time. ex: failed delivery. please retry or try again later.
you may also have troubled sending because your emails are not sent securely. an invalid SPF or DKIM or DMARC. Or even if the server sending is @hosting.com but you are using @gmail.com as tour forum email address. that is seen as spoofing to the receiving mail server.
there are many more scenarios than just these, for why your email was not delivered to that single email server. and remember, not all email servers are tied together.
note: typed from mobile. please excuse typos and the phone's auto-corrected shenanigans.
Last edited by isaac; 09/07/2018 2:01 PM.
