when trying to send a mail,it sends the following error to me:


Could not deliver message to the following recipient(s):

Failed Recipient: ai@hotmail.com
Reason: Failed four attempts to connect to the recipients mail server. No MX records were found for the 'hotmail.com' domain.Failed four attempts to connect to the recipients mail server.
Attempted to send the message to the following ip's:
64.4.33.7

I do not have problem with all the domains, single with some, like hotmail.

my reverse DNS installed and working.
And the record TXT to v=spf1 a mx-all


Help me pls.