I've been looking into this exact thing yesterday: Verizon's mail-to-sms
gateways. Might have been going on a long time and I’m just noticing.
No emails are accepted between 0:00 to 11:59 UTC time every day (the
deferrals during that time frame are a somewhat misleading AUP#CNCT from
Cloudflare)
Emails are accepted only between 12:00 to 23:59 UTC time every day.
12 UTC is 7 EST
So in my opinion this looks like an enforced “do not disturb” by Verizon
to ensure SMS delivery only between 7am to 7pm EST time - during the
"social hours" or whatnot. At least one other ESP I have contact with
has confirmed they're seeing exactly the same time frames.
I'm not a fan of the somewhat unclear bounce/deferral string they're
returning but I don't think Coudflare is doing it on their own, it's too
clean of a cutoff time - probably a Verizon rule.
On 01/06/2023 02:22, Zube via mailop wrote:
This is new as the past few days and rather odd.
Mail sent through the Verizon email-to-text gateway is fine during
the day when the relay is:
relay=vrz-mms.mx.a.cloudfilter.net. [52.37.233.84]
or
relay=vrz-mms.mx.a.cloudfilter.net. [35.169.108.175]
but starting somewhere around 5pm MST, mail sent to vtext.com,
vzwpix.com or mypixmessages.com is deferred:
relay=smtpin02-mms.vzw.a.cloudfilter.net. [52.33.196.155],
dsn=4.0.0, reply=421 vrz-ibgw-6003a.ext.cloudfilter.net
Mail sent from gmail makes it through.
Sometime around 5am the following day, a resend of the mail makes
it through again, but then it's hitting one of the two other servers
listed above.
I'm not the only one seeing this:
https://community.verizon.com/t5/Verizon-Messages/Vtext-messages-Severe-Delay/td-p/1240767/page/7
Going the other way, text-to-email seems to work fine and it arrives from
(in one test) twbgohaavzwvcmta-c-nk-x-00-sms-02.vtext.com [63.55.64.200]
after first going through m04.vzwpix.com (unknown [63.59.66.15])
If anyone from Verizon or cloudfilter.net is listening, please
advise.
Cheers,
Zube
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