Why does Gmail delay outgoing email? (for up to two days)

sites.inka.de

3 points·feklee··5 comments

That message is short and consists of just a link to something, and one of the addresses may be tainted by recent SPF failures. At a guess, some heuristics may have decided to wait a little and see if that URL goes away due to abuse complaints.

For the record, I also see delays with messages that primarily contain text, though many or all of these messages also contain a URL somewhere.

Welcome to the 1980s: SMTP is a best-effort, store-and-forward protocol - the fact that 90% of e-mail is delivered, that it's delivered near-instantly and that it's delivered directly(tm) to the destination server, now these are just accidental properties. In reality, there's no guarantee on any of these - there is even no guaranteed upper bound, e-mails can, in some cases, take weeks to be delivered.

TL;DR: e-mail sucks, do not depend on it.

That said, this seems to be the actual culprit: `softfail (google.com: domain of transitioning @gmail.com does not designate 2a04:c9c7:0:1073:217:a4ff:fe3b:e77c as permitted sender)`

The `Received-SPF: softfail` header is added between mail-oi0-f43.google.com and mail.inka.de. There is only a delay of one second.

The two day delay, however, happens on the sender's side, between the Google SMTP servers 10.202.76.146 and mail-oi0-f43.google.com.

In general, email received from Gmail users is delayed, often for one/two hours, rarely for a day or more.

In that case, that's e-mail working as designed. Adjusting expectations might be in order - and perhaps adopting an alternate protocol suitable for reliable+fast message delivery.

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