tools / Email

SMTP submission test

Connect to a mail server's submission port and check its banner, STARTTLS and login options.

Result connectedProtocol STARTTLSTLS yesTime 118 ms

220 CH0PR13CA0022.outlook.office365.com Microsoft ESMTP MAIL Service ready at Fri, 30 Oct 2026 08:52:27 +0000 [08DF3616E879A7B8]

Capability	Meaning
`SIZE 157286400`	maximum message size 150 MB
`PIPELINING`	send commands in batches
`DSN`	delivery status notifications
`ENHANCEDSTATUSCODES`	detailed status codes
`AUTH LOGIN XOAUTH2`	login mechanisms
`8BITMIME`	8-bit message bodies
`BINARYMIME`
`CHUNKING`	BDAT transfers
`SMTPUTF8`	UTF-8 addresses

SIZE 157286400 · PIPELINING · DSN · ENHANCEDSTATUSCODES · STARTTLS · 8BITMIME · BINARYMIME · CHUNKING · SMTPUTF8

ms		Line
0	·	Connecting to smtp.office365.com:587
21	·	Connected
33	←	`220 CH0PR13CA0022.outlook.office365.com Microsoft ESMTP MAIL Service ready at Fri, 30 Oct 2026 08:52:27 +0000 [08DF3616E879A7B8]`
33	→	`EHLO tools.mikepage.nl`
45	←	`250-CH0PR13CA0022.outlook.office365.com Hello [2a09:bac1:76e1:53d8::412:14]`
45	←	`250-SIZE 157286400`
45	←	`250-PIPELINING`
45	←	`250-DSN`
45	←	`250-ENHANCEDSTATUSCODES`
45	←	`250-STARTTLS`
45	←	`250-8BITMIME`
45	←	`250-BINARYMIME`
45	←	`250-CHUNKING`
45	←	`250 SMTPUTF8`
45	→	`STARTTLS`
57	←	`220 2.0.0 SMTP server ready`
57	·	Upgrading to TLS
57	·	TLS handshake done
57	→	`EHLO tools.mikepage.nl`
106	←	`250-CH0PR13CA0022.outlook.office365.com Hello [2a09:bac1:76e1:53d8::412:14]`
106	←	`250-SIZE 157286400`
106	←	`250-PIPELINING`
106	←	`250-DSN`
106	←	`250-ENHANCEDSTATUSCODES`
106	←	`250-AUTH LOGIN XOAUTH2`
106	←	`250-8BITMIME`
106	←	`250-BINARYMIME`
106	←	`250-CHUNKING`
106	←	`250 SMTPUTF8`
106	→	`QUIT`
118	←	`221 2.0.0 Service closing transmission channel`

Runs over a raw TCP socket from the Worker. Workers cannot open port 25, so this tests submission, not relay.