Contacts re email deliverability problem to

Graham Freeman jahiel at
Sat May 15 00:33:59 UTC 2010

On 14 May 10, at 17:23 , Jaren Angerbauer wrote:

> I just tested, and was able to successfully send an email to my
> Tmobile address [myphone#]  Are you getting bounces /
> failures back that are of any use?  Also FWIW (and sanity check) any
> reason why your client wants to use email-to-SMS, rather than just
> SMS.  From what I understand email-to-sms isn't the best platform for
> getting messages to mobile devices but I may be missing some
> client-specific visibility.

Hi, Jaren,

Delivering SMS-to-SMS would be impractical and prohibitively expensive.  This is for an iPhone messaging app that optionally delivers messages to SMS recipients for free.  The business model depends on email-to-SMS gateways.

Like you, we were able to deliver messages in low volumes, but as the app became increasingly popular (at one point in the Top 20 in the App Store) the volume exceeded a opaque-to-us rate limit at Tmobile, but not at other mobile providers - some of whom we're sending many more messages than we ever tried to deliver to Tmobile.

Two examples out of thousands:

>> Apr 30 23:52:52 postfix/error[17836]: [ID 197553] D44451D9570: to=<[xxxxxxxxxx]>, relay=none, delay=80196, delays=80195/0.18/0/0, dsn=4.0.0, status=deferred (delivery temporarily suspended: host[] refused to talk to me: 421 closing connection)
>> May  1 16:17:58 postfix/smtp[24906]: [ID 197553] 7CC5D1E9D7F: to=<[xxxxxxxxxx]>,[]:25, delay=59233, delays=59229/0/4.2/0, dsn=4.0.0, status=deferred (host[] refused to talk to me: 421 closing connection)



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