Which version of phpmailer are you using ? can you please post link here?

What version, what server setup, is it form in 3rd party plugin?

how to know with 3rd party plugin wrong.

For finding out which plugin (if any) is causing the problem:

1. disable ALL 3rd party plugins including your theme plugin (in case you use any). Does the error still occur then? If not, you know that the issue is caused by one the 3rd party plugins. If the error still occurs, the reasons for the error is probably not caused by a 3rd party plugin.
2. Enable your 3rd party plugins again step by step. If the error starts to appear again the last plugin enabled is causing the problem.

Like candidates: any plugins that modify login/site registration (e.g. adding registration with external account credentials like FB, Twitter etc.).

Hello mate, give CometChat a shot, it works smoothly on my website.

I've been using CometChat. Their offerings are pretty good, the most impressive one being video conferencing & their new  Hang out theme. For my website, I got the application customized a bit. Their support team was very helpful and i must say they have a lot of patience :) They have ready elgg integration so installation was fairly simple.

@Revletta - You joined just 18 minutes ago to say this?
Have you test used the community plugins / mods for Elgg chat?

It will be very nice if you or anyone post an objective comparison of the 5 or 6 chat solutions available for Elgg 1.8.19  (and also for the 1.9 github version).

That's not a bug. If you don't want to enter the username/password everytime, just check the 'remember me' box on your site login.

Rodolfo Hernandez

Arvixe/Elgg Community Liaison