Was anyone able to solve this? having the same problem
Not receiving mail - but can send it from server
To make sure your email setting is good then test it using: https://mxtoolbox.com/diagnostic.aspx
You then must fix any error occurred. Usually user forgot to set rDNS, wrong MX address or wrong SPF Record.
a month later
I was with same issue and solve by myself 
I change the postfix port to 587 because here in Brazil the 25 port is blocked (to block spammers)
nano /etc/postfix/master.cf
I edited:
##smtp inet n - n - - smtpd
587 inet n - n - - smtpdSo I could to send emails but not to receive.
The trick is Firewall > Port forwarding > redirect port 25 to 587
Hello I just have this problem if I can send mails but I can not receive them I have to do what you say?
?????
tuna I am able to send but not receive emails, I can send but not receive.
I was facing same issue but for Gmail I can send mail but can't receive from mail from Gmail. This happen may be because of SSL not configured on your mail server. After setting up SSL on domain and on mail server not mail coming in mail server from Gmail. May be that will help you or other out.
manthanesc Please how did yours come with automatic ssl for the email?
Joemires Hello, you can see his screenshot, the yellow place, there will be deployment of SSL related functions
aaP_richardreoc
The target ip is wrong.. Put your aapanel ip
Joemires
just click on yellow.
the auto generate certificate like:
*.site.com
site.com
Copy and paste it from email to the websites instead auto generate again.
4 months later
Hello guys! I have the same issue and I solved it by opening the right ports on the hosting side, not just on the aapanel.
Rigth ports are 110, 995, 143, 993, 25, 465, 587
With this and all the green marks and the SSL in place, everything works great!
Regards
2 months later
All my ports are open 
but i only receive the email i cannot send it even though it says sent successfully
aaP_morimartin
Still i am unable to send email and recive, can you please help me out ?
17 days later
same to me, i can send email, but can't receive mail from outside. all status like mx record, A record, SPF, DKIM, and DMARC already green tick, ports are open, SSL already active too.
aaP_wakpedwakyeng
Hello, may I ask whether your security group has opened relevant ports, and whether the service provider has opened relevant ports.
8 days later
I don't think, aapanal support team don't have any solution for incoming mails.
2 months later
Hi
What I did is to create a mail.mydomain.com , SSL it with letsencrypt. After which I simply copied and pasted the certificate into mail server->add ssl->other certificated.
That seemed to have done the trick.
- Edited
aaP_richardreoc
Sorry I replied wrong. Put the ip 0.0.0.0. I think it's a better pratice than aapanel ip
2 months later
hi
login to server with ssh
disable ufw
#ufw disable
worked
6 months later
I have same Problem all dns records is fine But I can not receive mails yet, also I tried to turn off ufw but not works!
Anyone, Anyway?