Over the last couple of weeks have had this problem using Shaw Webmail:
(1) Some e-mails sent by me not received by the other person although there is a copy in my "Sent" file.
(2) Some e-mails (including e-mail responses) sent to me not appearing in my in-basket. How do I know? The people have phoned to ask "Why don't you ever answer your e-mail?"
(3) All incidents involve conversations with someone outside Alberta (I am in Calgary) but this could be coincidence.
This is happening a lot and causing difficulties. For example, two hotel reservation requests were not delivered - with negative consequences.
I know about the spam filter and have carefully checked settings. Any suggestions would be appreciated.