DNS Failure

Hello dear, am having an issue with domains live service.

am using ur platforms more than 1 year. and everything was working perfectly

i have 5 email on my account 

*** Email address is removed for privacy ***
*** Email address is removed for privacy ***
*** Email address is removed for privacy ***
*** Email address is removed for privacy ***

all this email i don't know the password and i need to reset them, without delete the content emails ( but i know the default pass tayssir03529929)

now am facing another problem with this email:

*** Email address is removed for privacy ***

if i send an email from *** Email address is removed for privacy *** to *** Email address is removed for privacy *** , i got an failure email.

but if i send an email from *** Email address is removed for privacy *** to *** Email address is removed for privacy *** i receive the email.

i contact my hosting support they told me that everything is okay, dns and configuration 

and they ask me to contact you

i created a new email, *** Email address is removed for privacy ***, i send and i receive and email from it without any problem

so i don't know from where the problem, and why some email working and other no,

please i think skyla-lb.com need to be refreshed or configuration, please can you do ur test, also i need to reset all emails password 

ALL EMAILS 

and thank you so much