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LimeSurvey version: Version 2.50+, Build 160620
Own server or LimeSurvey Cloud: Own server (a VPS on BlueHost)
Survey theme/template: default template
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Hello.

I recently changed the domain name for my website. After doing this, our site's Lime Survey submissions still work, but the submissions no longer send e-mails.

I've changed in the database every instance of my old domain to my new domain, and the new domain does show on the Lime Survey forms, but the e-mail issue remains.

I've tried to use both PHP and SMTP mail settings without success. With the PHP mail setting, after I set in the config.php the debug value to 1, I see lots of warnings on the various Lime Survey survey pages (deprecation warnings only), but having that value set to 1 disallows the actual form submission (lots of warnings are shown after clicking submit and the form doesn't appear to get past those warnings).  With the STMP mail setting, the submission is sent, but no e-mail in sent.  I can't find anything else to change, and I can't find any log files for an error in sending the e-mails.

Will you please give me some advice on what else I can try to get the e-mails for the submissions working?  I realize we are using a very old version of the Lime Survey (our php version for the survey is 7.4!), and maybe that is the problem.  Please note that we had to create a subdomain to support php 7.4 on our server.  This might also be part of the problem, but I think it's probably mostly or entirely domain related, as the problem only began once we changed the domain name.

Thank you.

Donna

LimeSurvey version: Version 2.50+, Build 160620

So you are running a Limesurvey Version that hasn't been updated for over 10 years. Over a decade. We are at end of August 2026, your version came out in June 2016. This is ancient. And to make things worse, the 2.50+ version of Limesurvey was probably the worst release ever. It had so many issues and you never adopted any of the bug fixes, as the Version 2.50+ was the first release of this version. I highly recommend NOT to use this version in an productive environment. Not only today, but also on in June 2016.

Will you please give me some advice on what else I can try to get the e-mails for the submissions working?  I realize we are using a very old version of the Lime Survey (our php version for the survey is 7.4!), and maybe that is the problem.  Please note that we had to create a subdomain to support php 7.4 on our server.  This might also be part of the problem, but I think it's probably mostly or entirely domain related, as the problem only began once we changed the domain name.

Well, at least you are recognizing already that this is ancient. 
Here you can find the PHP requirements  for different Limesurvey versions, your version is not listed anymore (not overly surpising, given that it is a decade old).
www.limesurvey.org/manual/Installation_-_LimeSurvey_CE

As LS 3 supported (it is also already EOL for quite a while!) up to PHP 7.4 there is a very good chance that the LS 2.50 branch did not support PHP 7.4 yet.

I don't think it is worth troubleshooting an installation that runs a branch of Limesurvey that is EOL for such a long time (and there are serveral branches in between which today are already EOL). 

However, I agree it is mostly related to your domain and the DNS/MX settings or the settings of the email server. But this is out of the range of this forum I think. You will need to talk to the server admin, responsible for the DNS and MX settings.