I Tried to run the test with imaptest and got a segfault error. Debug:

Reading symbols from imaptest...done. (gdb) run user="puser%d@am.local" users=0-100000 pass=Us123456 host=ha- rr.am.local ssl=any-cert clients=100000 port=993 - secs=300 no_pipelining Starting program: /usr/bin/imaptest user="puser%d@am.local" users=0- 100000 pass=Us123456 host=ha-rr.am.local ssl=any-cert clients=100000 port=993 - secs=300 no_pipelining [Thread debugging using libthread_db enabled] Using host libthread_db library "/lib/x86_64-linux- gnu/libthread_db.so.1". Logi Sele Logo 100% 100% 100% 179 163 154 551/637 [0%] 245 247 250 1153/1372 [1%] 238 240 238 1725/2086 [2%] 213 215 219 2250/2725 [2%] 213 209 203 2760/3364 (263 stalled >3s) [3%] 220 226 228 3308/4024 (854 stalled >3s) [4%] 247 245 247 3870/4765 (1338 stalled >3s) [4%] 239 237 239 4414/5482 (1800 stalled >3s) [5%] 259 257 259 4998/6259 (2299 stalled >3s) [6%] 270 274 271 5599/7069 (2809 stalled >3s) [7%] 3843 46 26 ms/cmd avg Logi Sele Logo 100% 100% 100% 243 242 237 6122/7798 (3369 stalled >3s) [7%] 242 239 237 6697/8524 (3937 stalled >3s) [8%] 241 241 248 7251/9247 (4542 stalled >3s) [9%] 229 231 234 7776/9934 (5143 stalled >3s) [9%] 230 228 225 8332/10624 (5800 stalled >3s) [10%]

Program received signal SIGSEGV, Segmentation fault. 0x00007ffff7f1745f in io_loop_handler_run_internal () from /usr/lib/dovecot/libdovecot.so.0

How can I fix this?

I had this years ago, maybe you can find it here on the mailing list. I can't remember how I solved this or if I ever did. I can remember that things went better when I was using a clean mailbox (without messages)