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have you tried with TIdSMPT (indy components) ?<br />
<a href="https://www.experts-exchange.com/questions/20377428/TNMSMTP-problem.html?&anchorAnswerId=7361947#a7361947" rel="ugc">https://www.experts-exchange.com/questions/20377428/TNMSMTP-problem.html?&anchorAnswerId=7361947#a7361947</a><br />
<br />
it seems to be the component itself too:<br />
<a href="https://www.experts-exchange.com/questions/21274554/Authentication-failure-using-TNMSMTP-and-Delphi-6.html" rel="ugc">https://www.experts-exchange.com/questions/21274554/Authentication-failure-using-TNMSMTP-and-Delphi-6.html</a>
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have you tried with TIdSMPT (indy components) ?
https://www.experts-exchange.com/questions/20377428/TNMSMTP-problem.html?&anchorAnswerId=7361947#a7361947 [https://www.experts-exchange.com/questions/20377428/TNMSMTP-problem.html?&anchorAnswerId=7361947#a7361947]

it seems to be the component itself too:
https://www.experts-exchange.com/questions/21274554/Authentication-failure-using-TNMSMTP-and-Delphi-6.html [https://www.experts-exchange.com/questions/21274554/Authentication-failure-using-TNMSMTP-and-Delphi-6.html]

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Hello everyone, I'm using TNMSMTP for quite a while now to send emails and it works perfectly.<br />
<br />
This week, &nbsp;I'm getting an authentification error on one of my new customers which use a different internet supplier. &nbsp; They say that there's no identification needed but I still can't get through, any ideas on this one?
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Hello everyone, I'm using TNMSMTP for quite a while now to send emails and it works perfectly.

This week,  I'm getting an authentification error on one of my new customers which use a different internet supplier.   They say that there's no identification needed but I still can't get through, any ideas on this one?

TNMSMTP authentification error

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