Email
Mail server and MX port test
Test MX, SMTP/IMAP/POP3 ports and email DNS records.
Inbound mail needs valid MX, A/AAAA and preferably SPF/DMARC. Outbound needs 25, 465 or 587 reachable.
The tool lists MX, connects to the highest-priority host and probes SMTP/IMAP/POP3. The banner hints at the software.
A closed port can be firewall, host policy or IPv6 mismatch. Many ISPs block 25 on residential lines.
STARTTLS is 587, implicit TLS 465, classic SMTP 25. IMAP 143/993, POP3 110/995. Banners can leak software versions; keep them short in production.
Frequently asked questions
If 25 is closed, can I still send mail?
Most providers use 587 (STARTTLS) or 465 (SMTPS). Closed 25 alone is not fatal.
Do I need IPv6 MX?
Not required. An MX with AAAA can receive from IPv6 senders.
How are several MX ordered?
Lower preference is tried first. Equal values are for load sharing.
What does timeout mean?
Firewall, blackhole or distance. It is not proof the port is closed.
Are SPF/DMARC in this test?
Yes, domain DNS is fetched. Full policy lives on the SPF and DMARC tools.