Cannot connect with Microsoft outlook

hmfaysal commented 1 year ago

Great email server, thank you. The reason I am writing here is that I had been having issues while connecting with Microsoft outlook. I have tried many things, but could not manage to connect. Apple mail works fine, other imap, smtp clients connect and work smoothly.

The error message I get on the Microsoft Outlook Client is as follows:

We couldn't connect to the outgoing (SMTP) server. Please check your email address and password and try again.

Here is the log the server outputs while trying to connect with outlook.

l=info m="new connection" pkg=imapserver remote=███.███.███.███:52746 local=███.███.███.███:993 tls=true listener=public cid=189998ea1b8 delta="30.911µs" l=debug m="imap command done" pkg=imapserver cmd=capability duration="47.831µs" cid=189998ea1b8 delta=158.584929ms l=debug m="imap command done" pkg=imapserver cmd=login duration=2.176562ms cid=189998ea1b8 delta=72.130866ms username=████████@████████.██ l=debug m="imap command done" pkg=imapserver cmd=enable duration="55.851µs" cid=189998ea1b8 delta=73.566251ms username=████████@████████.██ l=info m="imap command ioerror" err="get line: unexpected EOF (fatal io error)" pkg=imapserver cmd=idle duration="104.943µs" cid=189998ea1b8 delta=78.136528ms username=████████@████████.██ l=info m="connection closed" err="get line: unexpected EOF (fatal io error)" pkg=imapserver cid=189998ea1b8 delta="150.823µs" username=████████@████████.██ l=info m="new connection" pkg=smtpserver remote=███.███.███.███:52747 local=███.███.███.███:465 submission=true tls=true listener=public cid=189998ea1b9 delta="46.041µs" l=debug m="smtp command result" pkg=smtpserver kind=submission cmd=ehlo code=250 ecode= duration="22.631µs" cid=189998ea1b9 delta=173.304877ms l=debug m="smtp command result" pkg=smtpserver kind=submission cmd=auth code=235 ecode=2.7.0 duration=64.794801ms cid=189998ea1b9 delta=137.004119ms username=████████@████████.██ l=debug m="smtp command result" err="bad syntax: expected \"<\" (remaining \" <████████@████████.██>\")" pkg=smtpserver kind=submission cmd=mail code=501 ecode=5.5.2 duration="32.931µs" cid=189998ea1b9 delta=91.181126ms username=████████@████████.██ l=info m="connection closed" err="read: EOF (fatal io error)" pkg=smtpserver cid=189998ea1b9 delta=84.716772ms username=████████@████████.██ l=info m="connection closed" err="write: EOF (fatal io error)" pkg=imapserver cid=189998ea1ad delta=16m4.652620931s l=info m="new connection" pkg=imapserver remote=███.███.███.███:57902 local=███.███.███.███:993 tls=true listener=public cid=189998ea1ba delta="28.871µs"

Any help is appreciated.

mjl- commented 1 year ago

It looks like the client is sending an invalid MAIL FROM command:

l=debug m="smtp command result" err="bad syntax: expected \"<\" (remaining \" <████████@████████.██>\")" pkg=smtpserver kind=submission cmd=mail code=501 ecode=5.5.2 duration="32.931µs" cid=189998ea1b9 delta=91.181126ms username=████████@████████.██

This is explicitly mentioned as invalid in the RFC about SMTP, 5321, see section https://datatracker.ietf.org/doc/html/rfc5321#section-3.3, which says:

   Since it has been a common source of errors, it is worth noting that
   spaces are not permitted on either side of the colon following FROM
   in the MAIL command or TO in the RCPT command.  The syntax is exactly
   as given above.

However, that doesn't help you much.

Mox doesn't allow it, as it is normally a sign of spammers with a sloppy SMTP implementation. But this is for submission, after you have authenticated. I think we can allow that space (except when in pedantic mode), instead of punishing all users of clients that do this.

Which version and platform of Outlook is this?

mjl- commented 1 year ago

You could try this diff, see if that gets you further:

diff --git a/smtpserver/server.go b/smtpserver/server.go
index 6346e28..f38e255 100644
--- a/smtpserver/server.go
+++ b/smtpserver/server.go
@@ -1203,6 +1203,10 @@ func (c *conn) cmdMail(p *parser) {
    }()
    p.xtake(" FROM:")
    // note: no space after colon. ../rfc/5321:1093
+   // Only allow illegal space for submission, not for regular SMTP. Outlook does this.
+   if c.submission && !moxvar.Pedantic {
+       p.space()
+   }
    rawRevPath := p.xrawReversePath()
    paramSeen := map[string]bool{}
    for p.space() {
@@ -1331,6 +1335,10 @@ func (c *conn) cmdRcpt(p *parser) {
    // ../rfc/5321:1985
    p.xtake(" TO:")
    // note: no space after colon. ../rfc/5321:1093
+   // Only allow illegal space for submission, not for regular SMTP. Outlook does this.
+   if c.submission && !moxvar.Pedantic {
+       p.space()
+   }
    var fpath smtp.Path
    if p.take("<POSTMASTER>") {
        fpath = smtp.Path{Localpart: "postmaster"}

hmfaysal commented 1 year ago

Thanks for the quick reply, I am using Microsoft Outlook 365 Apps for enterprise Version 2306 (Build 16529.20182).

I am going to try the git diff and get back to you. Fingers crossed.

hmfaysal commented 1 year ago

The git diff worked great. Thank you so much, everything working.

mjl- commented 1 year ago

Excellent, will commit this. Thanks for the clear report and quick testing!