When I send it, it appears as sent with no mention of any problem, but my recipient never gets it, not even in the Spam folder.

Same for receiving, I have a secondary e-mail address, and my main e-mail address is listed in the recipients list, but I never get it on my main e-mail address.

This problem seems to occur more frequently with one particular domain (transperfect.com).

Thanks in advance for any help.