stoli php mail function not working

[relay162]

Hello. The php mail function seems not to be working on stoli server. When used, the mail function hangs for a long while and eventually returns bool(false). This has been occurring for a couple of days. Please help.

[relay162]

php mail on stoli still seems to be failing.

[relay162]

php mail on stoli still not working.

[relay162]

Just tested again. php mail on stoli is still not working. This has worked previously. What is happening?

[relay162]

After stoli came back on-line today, php mail is working again. I'm assuming this has something to do with the chassis swap performed in the last day.

[relay162]

The php mail function no longer hangs and now returns bool(true), but the mail never seems to arrive.

[relay162]

Today the php mail function is returning bool(false), meaning not accepted for delivery.

---------- Post added at 09:05 PM ---------- Previous post was at 02:20 PM ----------

The php mail function is returning bool(true) now. However, there is still no mail received. I tried an additional test:
1. Using cPanel created new email account for previously configured sub-domain.
2. Logged into this email account using cPanel Webmail (roundcube) and sent test email to recipients at various domains.
None of the recipients receive the test email. What do you think?

[relay162]

When sending from roundcube on stoli, the message is immediately returned.

Mail delivery failed: returning message to sender

[relay162]

Still trying to send mail using roundcube on stoli, but the message is immediately returned:

From: Mail Delivery System <Mailer-Daemon@stoli.x10hosting.com>
Subject: Mail delivery failed: returning message to sender

[relay162]

mail seems to be working again today.