DNS SRV Autodiscover lets supporting email clients automatically detect the mail server settings for your domain by checking DNS values for your domain.
To set up Autodiscover you need to set up specific DNS records for your domain. You need to create the following DNS records on your domain. (See RFC 6186 for full details)
For the sake of the example, we will assume that your domain name is example.com and your mail server is on vpop3.example.com.
The DNS records below are in the standard BIND format.
Outgoing email
Create an SRV record with the following details
_submission._tcp.example.com IN SRV 0 1 25 vpop3.example.com
Name |
"_submission._tcp."<domain> |
Address class |
"IN" (Internet) |
DNS record type |
"SRV" |
Priority |
"0" |
Weight |
"1" |
Port |
This is the SMTP service port in VPOP3, eg 25 or 587 |
target |
This is the DNS name of the VPOP3 mail server |
Incoming email
For POP3, create an SRV record with the following details
_pop3._tcp.example.com IN SRV 0 1 110 vpop3.example.com
Name |
"_pop3._tcp."<domain> |
Address class |
"IN" (Internet) |
DNS record type |
"SRV" |
Priority |
"10" |
Weight |
"1" |
Port |
This is the POP3service port in VPOP3, eg 110 |
target |
This is the DNS name of the VPOP3 mail server |
For IMAP4, create an SRV record with the following details
_imap._tcp.example.com IN SRV 0 1 143 vpop3.example.com
Name |
"_imap4._tcp."<domain> |
Address class |
"IN" (Internet) |
DNS record type |
"SRV" |
Priority |
"0" |
Weight |
"1" |
Port |
This is the IMAP4 service port in VPOP3, eg 143 |
target |
This is the DNS name of the VPOP3 mail server |
More information
The "Priority" value specifies the order the email client should try the SRV records in, with lower priorities being tried first. So, if you have VPOP3 Enterprise, you could add both the POP3 & IMAP4 details above - note that the priority of the POP3 service is higher than that of the IMAP4 service, so the email client should choose the IMAP4 service.
If you have forced TLS services in VPOP3, then you append 's' to the DNS record name, and adjust the service port accordingly, eg:
_submissions._tcp.example.com IN SRV 0 1 465 vpop3.example.com
_pop3s._tcp.example.com IN SRV 0 1 995 vpop3.example.com
_imaps._tcp.example.com IN SRV 0 1 993 vpop3.example.com
You can use this along with the unencrypted/opportunistic TLS services as appropriate, by adjusting the priorities, eg:
_submissions._tcp.example.com IN SRV 0 1 465 vpop3.example.com
_submission._tcp.example.com IN SRV 1 1 587 vpop3.example.com
_submission._tcp.example.com IN SRV 2 1 25 vpop3.example.com
_pop3s._tcp.example.com IN SRV 10 1 995 vpop3.example.com
_pop3._tcp.example.com IN SRV 11 1 110 vpop3.example.com
_imaps._tcp.example.com IN SRV 0 1 993 vpop3.example.com
_imap._tcp.example.com IN SRV 1 1 143 vpop3.example.com
This would publish all the available services & ports (assuming your system is configured appropriately) and the email client could detect which ones it wants to used based on your selected priorities.
