On 4/6/20 9:08 AM, Ashley Dixon wrote: > On Mon, Apr 06, 2020 at 08:41:20AM -0400, Michael Orlitzky wrote: >> There's no need, the SMTP specification says that senders must retry >> every message, and should continue retrying for at least 4 or 5 days: >> >> https://tools.ietf.org/html/rfc5321#section-4.5.4 > > That's a relief, cheers. > > Excuse the skeptic within me, but is it safe to assume this specification is > strictly followed by all mail-transfer agents ? I.e., are there any common > M.T.A.s which do not continue trying to send for a few days ? >
All real MTAs follow the specification. A few email service providers (think SendGrid, MailChimp, etc.) allow their users to configure how many retries will be made, and every once in a while you have users who set it to zero because they see a button and can't resist pushing it. But those emails are never anything critical to begin with, in my experience, and it's a rare problem nonetheless.
